Physics Revision: WJEC GCSE The Sciences (Double Award) · teaching from 2026 · first awarded 2028

This guide is for the replacement qualification, taught from 2026 and first awarded in 2028. The page shows Physics requirements plus shared skills and Unit 7; choose another science above to switch scope.

Qualification code: 3455QD

Start revising free

Course details

WJEC · GCSE WJEC GCSE The Sciences (Double Award) · Physics3455QDExam years · 2028

Assessment Six 75-minute written exams: Units 1–3 have 56 marks and contribute 14.3% each; Units 4–6 have 64 marks and contribute 15.7% each. Unit 7 comprises two of three external enquiries, contributing 10%. Units 1–3 are first available in summer 2027; the full qualification is first awarded in summer 2028.

Official WJEC specification (opens in a new tab)

Tick a point after revising it. Progress is saved on this device and does not measure mastery.

Reviewed course guidance

Revision points, with the explanation beside them

Open a point to read what to know, how to use it in an assessment, a plain-language explanation and a self-check. Answers stay hidden until you choose to reveal them.

Options and source

Unit 1 tier

Foundation
Higher

§5.3: different tiers across units

Unit 2 tier

Foundation
Higher

§5.3: different tiers across units

Unit 3 tier

Foundation
Higher

§5.3: different tiers across units

Unit 4 tier

Foundation
Higher

§5.3: different tiers across units

Unit 5 tier

Foundation
Higher

§5.3: different tiers across units

Unit 6 tier

Foundation
Higher

§5.3: different tiers across units

Motion, Graphs, and Stopping DistancesCore
Scope: Core · Topic 3.1 (core)
Open revision guidance
What to know
Motion is defined by distance, time, speed, and acceleration.
Speed = distance / time (units: m/s).
Acceleration = change in speed / time (units: m/s²).
Distance-time graphs show motion; gradient represents speed.
On a distance–time graph a horizontal section means stationary, while a straight rising section means constant speed. A curve becoming steeper means speeding up; a curve becoming less steep means slowing down. Describe the change qualitatively before attempting a calculation.
On a speed–time graph, a horizontal line means constant speed, a rising line means increasing speed and a falling line means decreasing speed. Calculating acceleration from its gradient and distance from its area are Higher applications.
Stopping distance = thinking distance + braking distance.
Thinking time (reaction time) is the delay before braking begins; thinking distance is the distance travelled during that delay. Braking distance is travelled after the brakes are applied until the vehicle stops.
Tiredness, alcohol and distraction can increase thinking time. Higher speed increases thinking distance for a given reaction time and increases the energy the brakes must transfer. Wet or icy surfaces, worn tyres and poor brakes can increase braking distance.
Speed limits reduce road risk, and MOT tests check specified aspects of vehicle roadworthiness. Passing a test does not guarantee safety in every condition or replace responsible driving.
What to do in an assessment
Calculate speed using the formula: speed = distance / time.
Calculate mean acceleration using the formula: acceleration = (final speed - initial speed) / time.
Convert units before substitution: 1 km = 1000 m and 1 hour = 3600 s, so 72 km/h = 72 × 1000 ÷ 3600 = 20 m/s. A journey of 240 cm in 1.5 s is 2.4 ÷ 1.5 = 1.6 m/s.
Describe motion using distance-time graphs (linear slope = constant speed).
Solve problems involving total stopping distance by adding thinking distance and braking distance.
Example: A car travels 100m in 5 seconds. Speed = 100m / 5s = 20m/s.
Example: A car speeds up from 0 to 20m/s in 4s. Acceleration = 20m/s / 4s = 5m/s².
For a distance–time graph, calculate speed from the change in distance divided by elapsed time. A straight section from (2 s, 8 m) to (6 s, 24 m) gives (24 − 8) ÷ (6 − 2) = 4 m/s, not 24 ÷ 6 merely because it is the final point.
Mean-acceleration investigation: use the teacher's low ramp or air track, two light gates and a protected stopping area. Fix a card of known length to the trolley. At each gate, speed = card length ÷ the short time the card blocks the beam. Use the logger's elapsed time between the corresponding speed measurements, then mean acceleration = (second speed − first speed) ÷ elapsed time. Release from the same point without pushing and repeat. Keep slope, trolley and card fixed; check the logger's units and timing settings. These short-interval speed estimates do not prove acceleration is constant.
Constructed ramp result: initial speed 0 m/s, final speed 0.8 m/s and elapsed time 2.0 s give mean acceleration (0.8 − 0) ÷ 2.0 = 0.4 m/s². This is the average over the interval, not proof of constant acceleration throughout.
Constructed stopping calculation: travelling at 20 m/s with a thinking time of 0.7 s gives thinking distance 20 × 0.7 = 14 m. Given a braking distance of 26 m, total stopping distance = 14 + 26 = 40 m. These are example inputs, not a Highway Code stopping-distance table.
Using supplied equation forms, thinking time = thinking distance ÷ speed gives 14 m ÷ 20 m/s = 0.7 s. If total stopping distance is 40 m and thinking distance 14 m, braking distance = 40 − 14 = 26 m.
In plain language
This topic covers how we describe objects in motion using speed and acceleration. We use mathematical formulas to calculate these values and interpret motion using graphs. We also look at road safety, specifically why it takes time for a vehicle to come to a stop and the factors that influence how long that takes.
Self-check
A vehicle travels 150m in 10 seconds. What is its speed?
Show the answer
Speed = distance / time = 150m / 10s = 15m/s.
View diagrams
Distance-time and speed-time representations
Constructed idealised distance-time vertices are (0 s, 0 m), (4 s, 8 m), (6 s, 8 m) and (8 s, 16 m): speeds are 2 m/s, stationary from 4-6 s, then 4 m/s. A separate common-tier speed-time graph rises from 0 to 8 m/s over 0-4 s; it is read qualitatively, with no Higher area or gradient calculation.
Constructed distance-time and speed-time graphs. Read quantities from the axes; a flat distance-time section represents rest.

Advanced Motion Graphs (Higher)Higher
Scope: Higher · Unit 3 tier: Higher · Topic 3.1 (higher)
Open revision guidance
What to know
The gradient (steepness) of a speed-time graph represents the acceleration of the object.
The area under a speed-time graph represents the total distance travelled by the object.
To find the area under a non-linear speed-time graph, count squares or use geometric approximations (e.g., triangles/rectangles).
What to do in an assessment
Calculate acceleration from a speed-time graph by finding the gradient: (change in y-axis speed) / (change in x-axis time).
Calculate distance travelled from a speed-time graph by calculating the area under the plotted line.
Example: If a graph shows a constant speed of 10m/s for 5 seconds, the area (distance) = 10m/s * 5s = 50m.
Worked example: a straight line on a speed–time graph shows speed increasing uniformly from 0 to 10 m/s over 5 seconds. The area is a triangle: distance = 0.5 × 5 s × 10 m/s = 25 m. Without the straight-line assumption, the endpoints alone do not determine this area.
Equation rearrangement is Higher. Substitute first: if speed = distance ÷ time, a speed of 12 m/s for 3 s gives 12 = distance ÷ 3, then distance = 12 × 3 = 36 m. For acceleration = (final speed − initial speed) ÷ time, 2 = (final speed − 4) ÷ 3 gives 6 = final speed − 4, so final speed = 10 m/s.
In plain language
A speed–time graph gives acceleration through its gradient and distance travelled through its area. Straight sections allow calculations with rectangles, triangles or trapezia; curved sections may require an estimate, so do not claim more precision than the graph supports.
Self-check
On a speed–time graph, a straight line shows a car accelerating uniformly from 0 to 20 m/s in 10 seconds. What is its acceleration and the distance travelled?
Show the answer
Acceleration = gradient = (20-0)/10 = 2m/s². Distance = area = 0.5 * base * height = 0.5 * 10s * 20m/s = 100m.
View diagrams
Higher speed-time gradient and area
Higher-only: the same constructed straight speed-time line rises uniformly from 0 to 8 m/s over 4 s. Its triangle area gives distance 16 m; its gradient gives acceleration 2 m/s². This represents uniform acceleration.
Higher worked example: uniform acceleration gives a straight speed-time line. Its gradient gives acceleration and its area gives distance travelled.

Energy Principles, Efficiency, and PowerCore
Scope: Core · Topic 3.2 (core)
Open revision guidance
What to know
Conservation of energy: energy cannot be created or destroyed, only transferred between stores.
Stores include kinetic in moving objects, gravitational when an object is raised, elastic in stretched or compressed materials, thermal in matter, chemical in fuels/food/batteries and nuclear in atomic nuclei.
Transfer pathways: mechanical, electrical, heating, and radiation.
Wasted energy: energy transferred to stores that are not useful (usually thermal).
Heat flow: transfers from higher temperature to lower temperature until thermal equilibrium is reached.
Percentage efficiency = (useful energy transferred ÷ input energy) × 100, or (useful power output ÷ input power) × 100. Use matching units and do not mix energy with power in one ratio.
Power: the rate of energy transfer (Power = Energy / Time, in Watts).
Describe start and end stores: a falling object loses gravitational energy and gains kinetic energy; friction also warms its surroundings. Stretching a spring increases its elastic store. Identify mechanically, electrically, heating and radiation as pathways rather than inventing a 'light store'.
Loft and cavity-wall insulation reduce transfer through roofs and walls; double glazing reduces window losses; draught exclusion reduces warm-air movement. These examples provide context: this unit asks you to analyse supplied data, not memorise an insulation list or detailed heat-transfer mechanisms. Reducing heating demand can lower energy bills and associated emissions; suitability, installation cost and expected savings affect cost-effectiveness.
Fuel-based generation is used because fuels can be stored and established plants provide controllable output, but burning fossil fuels releases carbon dioxide and may produce harmful pollutants. Fuel extraction and transport also have impacts.
Nuclear generation supplies large amounts of reliable electricity with low operational carbon emissions, but involves radioactive waste, high construction/decommissioning costs and safety responsibilities. Mining and construction mean its whole life cycle is not impact-free.
Wind drives turbines; hydroelectric and tidal systems use moving water; wave systems use motion of the sea surface; solar cells transfer energy electrically from sunlight, while solar thermal systems heat a fluid; geothermal systems use heat from Earth; biomass uses replenishable fuel when managed sustainably.
Renewables reduce dependence on finite fossil fuels, but wind and sunlight vary; sites, land use, materials, wildlife impacts and storage or backup matter. A renewable label alone does not mean no environmental effect.
Batteries can charge when electricity demand is low or generation is plentiful, increasing a chemical store, and supply the grid later. Pumped storage moves water uphill to increase its gravitational store, then releases it through turbines at high demand. Both lose some energy and are stores, not new primary energy sources.
Alternative fuels may reduce fossil-fuel dependence, but their production still needs resources and energy. Nuclear-power ethics weigh climate benefits and reliable supply against accident risks, waste management, future generations and who bears costs and risks.
The National Grid connects major generating stations and users, and supply must respond to changing demand. Stations differ in capacity and start-up time: flexible sources and storage help meet peaks while other sources provide continuing supply. Interconnectors allow electricity imports and exports with other European countries. Use supplied data to compare these options, including environmental impacts and reliability.
What to do in an assessment
Calculate efficiency: a battery-powered motor transfers 1000 J electrically from the battery's chemical store. The raised load gains 800 J in its gravitational store. Efficiency = (800 / 1000) × 100 = 80%. Electrical transfer is a pathway, not an extra energy store.
In a Sankey diagram, arrow-shaft widths are proportional to the energy transferred. The input must equal the sum of all outputs; wasted energy can be larger or smaller than the useful output.
Calculate electricity costs: if a 2 kW heater draws that power continuously for 5 hours, units used = 2 kW × 5 h = 10 kWh. At a supplied illustrative price of £0.20 per unit, the energy cost = 10 × 0.20 = £2.00. This excludes standing charges and does not assume a thermostat-controlled heater is always drawing full power.
Analyse payback time: Payback time = Initial cost of insulation / annual savings. If loft insulation costs £400 and saves £100 per year, payback is 4 years.
For the 1000 J motor example, complete a missing wasted output as 1000 − 800 = 200 J. Input, useful and wasted arrow widths have the ratio 10:8:2; efficiency is 800 ÷ 1000 × 100 = 80%.
Power example: transferring 600 J in 3 s gives 600 ÷ 3 = 200 W. One watt is one joule per second; convert watts to kilowatts before using an appliance cost calculation in kWh.
Use supplied units consistently: 3000 W = 3 kW and 30 minutes = 0.5 hours. At constant power, energy used = 3 × 0.5 = 1.5 kWh. With a supplied price of 24 p/kWh, cost = 1.5 × 24 = 36 p = £0.36.
Constructed insulation comparison: A costs £400 and saves £100/year; B costs £600 and saves £150/year. Both pay back in four years. After five years their net savings are £100 and £150 respectively, assuming unchanged yearly savings and no extra costs. A shorter stay or changed energy prices can change the decision.
In a fuel-based station, fuel burns in a furnace and the boiler heats water to produce steam. Steam drives a turbine connected to a generator. The starting store is chemical; useful energy is transferred electrically to the grid. Nuclear fission supplies heat from a nuclear store for a similar turbine–generator process. Know the furnace, boiler, turbine and generator functions; electricity is a transfer pathway, not an energy store.
Read supplied demand graphs and compare generating capacity and start-up times. In a constructed example, demand is 40 GW while the stated other generation supplies 38 GW: the 2 GW gap could be met by available flexible generation, storage or imports. Check supplied capacities rather than assuming one technology can meet any shortfall.
In plain language
Energy is conserved as it transfers between stores. A device is more efficient when a greater proportion of its input produces the intended useful output. Heating is useful in a heater but warming the surroundings may be unwanted in a motor. Insulation reduces unwanted energy transfer; kilowatt-hours measure electrical energy use, not power.
Self-check
A machine has a total power input of 500W and a useful power output of 400W. What is its efficiency and how much power is wasted?
Show the answer
Efficiency is (400/500) * 100 = 80%. The wasted power is 500W - 400W = 100W.
View diagrams
Worked energy transfers and efficiency
An illustrative motor transfers 800 J usefully from 1000 J electrical input; 200 J heats its surroundings. Arrow shafts have proportional widths 100, 80 and 20. Efficiency is 80%.
Constructed motor example: arrow-shaft widths represent transferred energy.

Forces, Newton's Laws, and Terminal SpeedCore
Scope: Core · Topic 3.3 (core)
Open revision guidance
What to know
Common forces include weight (gravity), friction, air resistance and other drag, thrust, lift, tension, normal contact reaction, elastic restoring forces, magnetic forces, electrostatic forces, and forces due to gas and radiation pressure.
Weight is the gravitational force on an object; mass is the amount of matter, measured in kg.
Weight (N) = mass (kg) × gravitational field strength (N/kg). Use the specification's given approximate Earth value of 10 N/kg unless the question supplies another value.
Newton's second law: resultant force F (N) = mass m (kg) × acceleration a (m/s²). It is the total resultant, not just one of several forces.
A resultant force can change an object's speed or direction. Balanced forces give no resultant and do not change its motion.
For a released object falling through air, weight acts downwards and drag acts upwards. Initially drag is small and the object accelerates; as speed rises drag increases, reducing the resultant and acceleration. When drag equals weight, the resultant and acceleration are zero and speed is constant.
A surface's normal reaction acts perpendicular to the surface; tension pulls along a taut rope; elastic forces oppose stretching or compression. Magnets and electric charges exert forces without contact. Gas pressure exerts forces on surfaces, and absorbed or reflected radiation can also exert a force; gas and radiation pressure feature in the star model. A force diagram shows forces acting on the selected object only, not the interaction partner's forces.
What to do in an assessment
Calculate weight: A 50kg object has a weight of 50kg × 10 N/kg = 500 N.
Represent forces with arrows on diagrams.
Calculate resultant force: 10N east and 3N west = 7N east.
Apply Newton's second law: A 2kg object accelerating at 3 m/s² requires 6N of force.
Apply the first law in a common-content example: a car moving at constant speed in a straight line has zero resultant force, although thrust and resistance may both be present. Balanced forces do not mean there are no forces.
Apply the third law in a common-content example: when one skater pushes another, the other skater pushes back equally in the opposite direction. These forces act on different skaters; they do not cancel as forces on one skater. The formal law statements are in the Higher lesson.
For forces in the same direction, add magnitudes: 4 N and 6 N right give 10 N right. For opposite directions, subtract: 10 N right and 3 N left give 7 N right. Label each arrow with the force and its direction.
Given g = 1.6 N/kg on the Moon, the same 50 kg object weighs 50 × 1.6 = 80 N, compared with 500 N using the specification's Earth value of 10 N/kg. Its mass remains 50 kg.
Terminal-speed investigation: drop cake cases only from the teacher's approved safe height; never climb or lean over a drop. Use video or suitable timing equipment to compare travel times through equal-distance zones lower in the fall. Repeated similar speeds in successive zones support terminal speed; timing the whole fall alone does not.
Compare different numbers of nested cases while keeping their frontal shape, release orientation and drop conditions as similar as possible. More weight needs more drag to balance it, usually giving a higher terminal speed. Repeat, account for flutter and check whether the available height is sufficient.
In plain language
Forces are pushes or pulls. An unchanged object's mass is the same on different planets, but its weight depends on gravitational field strength. Add the forces to find the resultant before using F = ma. In the falling-through-air model, terminal speed is reached when drag balances weight and acceleration becomes zero.
Self-check
An object of mass 5 kg has a resultant force of 20 N. Use the supplied form acceleration = resultant force ÷ mass to calculate its acceleration.
Show the answer
Using the supplied form, acceleration = 20 N ÷ 5 kg = 4 m/s².
View diagrams
Free-body diagram and resultant force
A free-body diagram for one body shows only its external forces: equal vertical normal contact force and weight, 20 N applied driving force right and proportionally shorter 5 N friction left. A separate panel shows the 15 N rightward resultant, not as an additional external force. For a 3 kg body the acceleration is 5 m/s².
Identify forces and their directions on a single object.

Advanced Applications of Newton's LawsHigher
Scope: Higher · Unit 3 tier: Higher · Topic 3.3 (higher)
Open revision guidance
What to know
Newton's First Law: a body remains at rest or moves at constant speed in a straight line unless acted upon by an external resultant force.
Newton's Third Law: if body A exerts a force on body B, body B exerts an equal-magnitude force in the opposite direction on body A. The forces belong to the same interaction and act on different objects, so they are not a cancelling pair on one object's force diagram.
What to do in an assessment
Apply Newton's first law to analyse bodies where the resultant force is zero (constant velocity).
Apply Newton's third law to identify and describe equal and opposite force pairs in dynamic systems, such as a rocket engine exhausting gas or two skaters pushing off each other.
In plain language
State the First and Third Laws precisely, then distinguish a zero resultant on one object from an interaction pair acting on two different objects. Their practical applications also appear in the common lesson; learning the formal statements here does not make all applications Higher-only.
Self-check
If a rocket exerts 10,000N of force on exhaust gases, what force do the gases exert on the rocket?
Show the answer
According to Newton's third law, the gases exert 10,000N of force on the rocket in the opposite direction.

Wave Properties and the Electromagnetic SpectrumCore
Scope: Core · Topic 3.4 (core)
Open revision guidance
What to know
Transverse waves have vibrations at right angles to energy transfer.
Longitudinal waves have vibrations parallel to energy transfer.
Sound is longitudinal; light and EM waves are transverse.
Amplitude is maximum displacement from equilibrium; frequency is complete oscillations per second in Hz; period is time per complete oscillation in s; wavelength is distance between neighbouring points at the same phase, such as crests or compressions, in m.
EM spectrum (low to high frequency): radio, microwave, infra-red, visible, UV, X-ray, gamma.
EM waves travel at the same speed in a vacuum.
X-rays, gamma rays and the highest-energy ultraviolet can ionise matter and damage cells. Ultraviolet can also damage DNA without ionising atoms; not every ultraviolet wavelength has the same effect. Exposure and shielding must be controlled, particularly in medical uses.
Towards the gamma end, wavelength is shorter and frequency and energy per photon are greater. This does not mean every weak gamma beam transfers more total energy than every powerful radio transmitter.
Ultrasound is sound above the usual upper human hearing limit, approximately 20 000 Hz. It is a mechanical wave, not electromagnetic radiation.
Radio waves carry broadcasts; microwaves carry satellite and mobile communications; infrared is used for thermal imaging and remote controls; visible light supports vision and optical communications; ultraviolet can sterilise surfaces; X-rays image internal structures; gamma radiation can treat cancers and sterilise equipment. These uses provide context rather than a required memorised list; apply wave properties to the situation supplied and weigh benefits against exposure risks.
In the ideal school model, particles oscillate about their positions while the wave transfers energy; the whole medium does not travel along with it. Electromagnetic waves do not need a material medium. 'Up and down' is one transverse example; the defining relationship is perpendicular to propagation, whatever the wave's orientation.
What to do in an assessment
Use T = 1/f.
Use v = f × λ (wave speed = frequency × wavelength).
Use speed = distance / time.
Calculate distance using echo delay: distance = (speed × time) / 2.
Draw wave diagrams indicating amplitude and wavelength.
On a displacement–distance graph, label wavelength between matching neighbouring points such as crest to crest, and amplitude from the equilibrium line to a crest, not crest to trough. On a displacement–time graph, the corresponding interval is period, not wavelength.
Constructed drawing task: amplitude 2 cm and wavelength 4 cm mean crests reach +2 cm, troughs −2 cm, and neighbouring crests are 4 cm apart on a distance axis. For period 0.5 s on a time axis, neighbouring crests are 0.5 s apart and frequency is 1 ÷ 0.5 = 2 Hz.
Constructed depth example: an ultrasound pulse in water travelling at a supplied 1500 m/s returns after 0.040 s. It travels 1500 × 0.040 = 60 m out and back, so the reflecting seabed is 30 m away.
In crack detection an unexpected internal echo can indicate a boundary or flaw; animals can use echo timing to locate objects. Radar uses radio waves or microwaves, not ultrasound, with the same out-and-back timing principle.
In plain language
Waves are oscillations that carry energy. In longitudinal waves, movement is back-and-forth like a slinky. In transverse waves, it is up-and-down like a rope. We measure these using frequency, wavelength, and speed. The electromagnetic spectrum is a family of light waves, ranging from long radio waves to highly energetic, ionizing gamma rays.
Self-check
A wave has a frequency of 50 Hz and a wavelength of 0.2 m. Calculate its speed.
Show the answer
Speed = frequency × wavelength = 50 Hz × 0.2 m = 10 m/s.
View diagrams
Wave profile, wavefronts and frequency
Amplitude and wavelength on a wave diagram.

The Solar System, Observations, and Star Life CyclesCore
Scope: Core · Topic 3.5 (core)
Open revision guidance
What to know
The Solar System formed from a nebula collapsing under gravity, creating a central protostar.
The four inner terrestrial planets are mainly rocky; the four outer giant planets are much larger and formed farther out. Jupiter and Saturn are mainly hydrogen and helium; Uranus and Neptune have larger proportions of heavier, icy materials and are often called ice giants.
Solar System components: Sun (star), planets, dwarf planets (e.g., Pluto), moons, asteroid belt (between Mars and Jupiter), Kuiper belt (beyond Neptune), and the Oort cloud (outer shell of the solar system).
Ground-based telescopes suffer from light pollution, atmospheric blurring, and limited electromagnetic (EM) radiation detection (mostly visible and radio).
Space-based telescopes avoid atmospheric obscuration but are very expensive.
For the Sun-like lower-mass pathway studied here: Protostar → Main Sequence → Red Giant → White Dwarf. Do not extend this sequence to every extremely small star.
High mass star life cycle: Protostar → Main Sequence → Red Supergiant → Supernova → Neutron Star or Black Hole.
During fusion stages, stars release energy by fusing light nuclei, initially hydrogen into helium; evolving stars can use successively heavier fuels. Different masses reach different stages and do not all fuse the same elements.
Stellar stability is maintained by a balance (hydrostatic equilibrium) between inward gravitational force and outward gas/radiation pressure.
The Sun is mainly hydrogen and helium and is far larger than any planet. Jupiter is the largest planet by diameter; the terrestrial planets are much smaller. Distinguish radius or diameter from mass when comparing data.
Dwarf planets such as Pluto orbit the Sun and are approximately round but have not cleared their orbital neighbourhood. Moons orbit larger bodies; most planets have moons, but Mercury and Venus do not. Comets are small icy and dusty bodies that can develop tails near the Sun; many have highly elongated elliptical orbits. The asteroid belt contains mainly rocky bodies and the dwarf planet Ceres between Mars and Jupiter.
The Kuiper belt is a region of icy bodies beyond Neptune, including Pluto, associated with many short-period comets. The much more distant Oort cloud is a proposed roughly spherical reservoir associated with long-period comets, not an observed solid shell.
Earth's atmosphere blurs images and absorbs many wavelengths; visible and radio windows allow some ground observations. Space instruments can observe wavelengths blocked below, but launch, maintenance and operation are expensive.
Astronomers internationally, including Wales-based researchers, collaborate on observations, instruments and data analysis. Combining different wavelengths and testing models against observations continues to improve understanding rather than providing a final picture of the Universe.
What to do in an assessment
Use supplied data to compare planet sizes, distances, masses and orbital periods; distinguish a conclusion supported by the data from an assumption about every object.
Analyse diagrams of star life cycles to identify stages based on mass.
High-altitude optical sites can reduce the amount of atmosphere above a telescope; remote dark sites reduce visible-light pollution. Radio telescopes need protection from radio interference, which is not the same as visible-light pollution.
Read a supplied atmospheric-transmission diagram: a high transmitted fraction means that wavelength can reach a ground telescope; a low fraction means much is absorbed. Compare optical/radio windows with blocked wavelengths when choosing a ground or space instrument. Do not assume every wavelength in a broad region passes equally well.
Constructed comparison using supplied rounded radii: 70 000 km ÷ 6400 km ≈ 11, so the larger body's radius is about eleven times the smaller's. This compares radius, not mass or volume; use the correct column and units.
Place planets in order outwards: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Match a star's stages to its mass category rather than mixing the red-giant and red-supergiant paths.
In plain language
The Solar System formed from a collapsing cloud of gas and dust. Rock-forming materials could condense in the hotter inner region. Farther out, colder conditions allowed ices to condense as well, helping large cores form and capture light gases such as hydrogen and helium. This does not mean hydrogen and helium condensed into ice at the planets' formation temperatures. Ground telescopes are affected by the atmosphere; space telescopes avoid it but are costly. A main-sequence star is stable when inward gravity balances outward effects of gas and radiation pressure.
Self-check
Which main stellar pathway includes a supernova, and how does its remnant differ from that of a Sun-like star?
Show the answer
The high-mass sequence includes a red supergiant and supernova, leaving a neutron star or black hole. A Sun-like lower-mass star becomes a red giant and later a white dwarf, without this supernova pathway.

Higher Physics: Stellar Equilibrium DynamicsHigher
Scope: Higher · Unit 3 tier: Higher · Topic 3.5 (higher)
Open revision guidance
What to know
In a stable main-sequence star, gravity and the pressure gradient balance; fusion supplies energy that helps maintain gas and radiation pressure.
Losing a source of fusion energy can reduce support; contraction heats the core and may allow later fusion stages. Outcomes depend on mass, and an expanding envelope does not imply an expanding core.
A white dwarf is not powered by ongoing nuclear fusion. Pressure of compressed matter supports the dense remnant while it cools; stopping fusion does not mean every possible supporting pressure instantly becomes zero.
What to do in an assessment
Explain the changing balance of gravity and pressure during main-sequence, giant and final-remnant stages. Do not invent a numerical force ratio when none is supplied.
For a massive star, failure of the core's support after successive fusion stages leads to collapse and a supernova, leaving a neutron star or black hole depending on the remnant. For a Sun-like star, outer layers are lost and a dense white dwarf remains and cools.
In plain language
Track the core and outer layers separately. When central hydrogen fusion declines, the core loses support, contracts and heats. Fusion in a surrounding shell helps the outer layers expand into a giant stage; helium fusion in the core can begin later in a Sun-like star. The core shrinking and the envelope expanding are not contradictory.
Self-check
How does the force balance change when a main sequence star evolves into a red giant?
Show the answer
Central hydrogen fusion declines, reducing support against gravity so the core contracts and heats. Hydrogen fusion in a surrounding shell supplies energy as the outer layers expand and cool. The core and envelope change differently; it is not simply the whole star expanding because helium instantly ignites.

Fundamentals of Radioactive Decay and Half-lifeCore
Scope: Core · Topic 6.1 (core)
Open revision guidance
What to know
In conventional nuclear notation ᴬ_ZX, X is the element symbol, A the nucleon number above and Z the proton number below; neutrons = A − Z. For ¹⁴₆C, there are 6 protons and 8 neutrons.
Isotopes are atoms with identical proton numbers but different neutron numbers.
Radioactive decay is the spontaneous, random process of unstable nuclei emitting radiation.
Alpha particles are helium nuclei (2 protons, 2 neutrons), beta particles are fast-moving electrons, and gamma rays are high-energy electromagnetic waves.
Ionising ability order: Alpha > Beta > Gamma; Penetration order: Gamma > Beta > Alpha.
Background radiation originates from natural sources (radon gas, cosmic rays, rocks) and artificial sources.
Half-life is the time taken for the activity or number of nuclei in a sample to decrease by half.
Activity is the number of nuclear decays per second; 1 becquerel (Bq) means one decay per second. Ionisation removes electrons from atoms and can damage living cells and their DNA.
Radioactive waste contains isotopes with different half-lives, requiring appropriate containment and monitoring. A short half-life does not by itself prove a sample is harmless.
Different dating isotopes suit different materials and timescales. Carbon-14 supports dating appropriate archaeological organic remains and sometimes forensic investigations; other isotope methods date much older rocks, helping constrain fossil ages from rock layers.
Alpha is strongly ionising and readily stopped by paper or the outer skin; beta is less ionising and stopped by suitable thin metal shielding; gamma is weakly ionising per path length and more penetrating, reduced by thick lead or concrete rather than perfectly blocked.
Radon is an important natural background source from radioactive decay in rocks and soils; local geology changes levels. Cosmic radiation is generally greater at higher altitude. Food/building materials also contribute. Population radiation-dose comparisons may include artificial medical exposures, but an intentional medical beam is not the ambient background count in a classroom.
Use actual dose and exposure data when comparing perceived risks. Medical exposures contribute substantially to artificial exposure, while normal nuclear-power operations contribute much less to average background exposure; accident risks and individual medical exposures are separate questions. Perceived benefit, trust and publicity also affect risk judgements.
What to do in an assessment
For background radiation, use the teacher's detector setup without an intentional source, count over a known interval and repeat. Divide total counts by time for a count rate. Random variation means a longer interval or repeated readings improves the estimate.
Constructed background calculation: readings of 18, 22 and 20 counts in three one-minute intervals give 60/3 = 20 counts/minute. A measured sample rate of 120 counts/minute gives corrected rate 120 − 20 = 100 counts/minute. Detector count rate is not automatically activity in Bq.
Convert detector units consistently: 120 counts/minute ÷ 60 = 2 counts/second. A detector records only some emissions, so this does not establish an activity of 2 Bq.
Read half-life from supplied decay data or a curve using the time between a corrected rate and half that rate. For 800 counts/minute at 0 h and 400 at 2 h, the half-life is 2 h. The interval from 400 to 200 should also be 2 h for the same isotope.
Select isotopes using the described application and supplied half-lives/radiation data. No fixed list of isotope names or industrial/medical methods needs recall. A tracer must remain detectable long enough for its intended examination without unnecessarily prolonged exposure.
Dice model: roll all remaining dice, remove sixes permanently and record the number remaining after each round. A die represents an undecayed nucleus; rounds represent equal time intervals, not automatically seconds. Repeat with small and large starting samples.
Larger samples usually have smaller relative random fluctuations and a smoother decay trend; one nucleus still has an unpredictable decay time. Coins or digital simulations can use a constant probability of decay per step.
Removing sixes gives a decay probability of 1/6 per fair die per round; removing heads gives 1/2 per fair coin. With equal-size samples and equal steps, the larger probability produces a faster average decline. Actual results fluctuate. Plot round number against undecayed objects, label axes and use an appropriate smooth best-fit trend rather than claiming every sample halves on exactly the same round.
Given carbon-14 curve points of 100% at 0 years, 50% at 5730 years and 25% at 11 460 years, read 11 460 years for remains at 25%. These are supplied illustrative curve points; carbon dating concerns once-living material, not every rock or fossil.
Balance a supplied alpha equation: ²³⁸₉₂U → ²³⁴₍?₎Th + ⁴₂He needs 90 beneath Th because 92 = 90 + 2. A supplied beta equation ¹⁴₆C → ¹⁴₍?₎N + ⁰₋₁e needs 7 because 6 = 7 − 1. Completing a supplied equation is common content; constructing one is Higher.
For a described medical tracer, choose gamma emission that can escape to a detector and a half-life long enough for the examination but short enough to reduce prolonged exposure. For thin-sheet thickness monitoring, beta's moderate penetration can be useful. Justify against the supplied application and isotope data.
Interpret absorber tables with unchanged detector geometry and background correction. Constructed school-model count rates per minute: background 20; source without absorber 320; with paper 220; with suitable thin aluminium 120; with thick lead 50. The large paper and aluminium reductions support alpha and beta components; the more penetrating remaining signal supports gamma. Sources can emit several types, and real measurements need repeats, uncertainties and appropriate absorber information.
In plain language
Unstable nuclei decay randomly by emitting particles or electromagnetic radiation. Half-life describes the time for the number of undecayed nuclei, or activity, to halve: matter does not simply disappear. Penetration, ionisation and half-life help determine suitable applications and precautions.
Self-check
A supplied curve has measured rates of 180 counts/minute initially and 100 after four days, with background 20 counts/minute. What is its half-life?
Show the answer
Subtract 20 from both measurements: corrected rates are 160 and 80 counts/minute. They halve in four days, so the half-life is four days.
View diagrams
Reading half-life from a supplied curve
A supplied illustrative background-corrected count-rate curve falls from 800 to 400 counts per minute in two hours. Read the half-life from the axes. No logarithmic representation or prediction equation is included.
Read the half-life from this supplied illustrative curve; it is not a set of measured results.

Advanced Decay Equations and KineticsHigher
Scope: Higher · Unit 6 tier: Higher · Topic 6.1 (higher)
Open revision guidance
What to know
Balance nucleon numbers on the top row and nuclear-charge/particle-charge values on the bottom row. For a nucleus, the bottom number is its proton number; the beta-minus electron's −1 denotes its negative charge, not a negative count of protons. Beta-minus decay increases the daughter's proton number by one.
Alpha decay equation: X(A, Z) -> Y(A-4, Z-2) + He(4, 2).
Beta decay equation: X(A, Z) -> Y(A, Z+1) + e(0, -1).
Activity/mass decay over time follows an exponential curve, where the rate of decrease slows as the remaining amount reduces.
What to do in an assessment
Construct a beta-minus equation: ¹⁴₆C → ¹⁴₇N + ⁰₋₁e. The nucleon number stays 14 and 6 = 7 + (−1); the electron is created in the nuclear decay, not ejected from an ordinary outer shell.
Construct an alpha equation: ²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He. Subtract 4 from A and 2 from Z, then identify the daughter element from its proton number.
For an initial activity of 1000 Bq and a three-day half-life, nine days is three half-lives: 1000 → 500 → 250 → 125 Bq. After two half-lives, 8 g of the original isotope leaves 2 g undecayed, alongside its decay products.
In plain language
Construct decay equations by tracking nucleon and proton numbers. Predict how activity or the mass of the original radioisotope changes over repeated half-lives. This means undecayed parent material, not all matter in a container disappearing.
Self-check
Construct the balanced equation for the beta decay of Thorium-234 (Th-234, Z=90) into Protactinium (Pa).
Show the answer
Th(234, 90) -> Pa(234, 91) + e(0, -1).

Wave Behaviour and Medical ImagingCore
Scope: Core · Topic 6.2 (core)
Open revision guidance
What to know
Visible light spectrum consists of individual colours.
Reflection sends waves back from a boundary. Refraction occurs with a change of wave speed across a boundary; direction usually changes, but not for a ray incident along the normal.
Surfaces appear coloured because they absorb specific wavelengths and reflect others.
Coloured filters transmit specific wavelengths while absorbing others.
Medical imaging utilises gamma rays (tracers), X-rays (2D/3D CT scans), ultrasound, and light (endoscopes).
Total internal reflection occurs when light travels from an optically denser material towards a less optically dense material and its angle of incidence exceeds the critical angle. Angles are measured from the normal.
In optical fibres, repeated total internal reflection keeps light inside the core, carrying communication signals or light and images in an endoscope.
A ray shows the direction of travel; a wavefront joins points at the same stage of a wave. Rays are perpendicular to plane wavefronts. On entering slower water or glass, wavelength decreases while frequency stays constant, and the ray bends towards the normal unless it enters along the normal.
What to do in an assessment
Draw ray diagrams showing angles of incidence and reflection for plane surfaces.
Draw ray diagrams showing the bending of light toward or away from the normal when entering denser or less dense media.
Draw the normal perpendicular to a reflecting surface, measure incidence and reflection from it and make i = r. Plane wavefronts must remain perpendicular to their ray directions.
For refraction into a slower medium, draw the ray closer to the normal and wavefronts closer together; the frequency is unchanged. Ripple-tank waves slow in shallower water. In light diagrams 'optically denser' refers to lower light speed, not simply greater mass density.
Read wavelength as the perpendicular distance between adjacent equivalent wavefronts, along the ray direction, using the diagram's supplied scale. Measuring along the boundary instead does not generally give wavelength.
Ideal colour example: under white light, a red filter transmits red and absorbs other colours. An ideal blue-reflecting surface under red light looks dark because no blue arrives to be reflected. White surfaces reflect a broad visible range; black surfaces absorb much of it.
For additive mixing of light, the primary colours are red, green and blue. Red + green gives yellow, green + blue cyan, and red + blue magenta; combining all three suitably gives white. Yellow, cyan and magenta are secondary light colours. This is light mixing, not the same rule as mixing paints.
Visible colours correspond to different wavelengths, from longer-wavelength red to shorter-wavelength violet. An ideal green filter under yellow light (red + green) transmits the green part; under blue-only light it transmits no light in the ideal model.
CT combines many X-ray views into cross-sectional images and possible 3D reconstructions; it gives detailed internal information but uses ionising radiation.
A gamma camera detects radiation emitted by a tracer placed inside the body, mapping its distribution and organ activity. It involves ionising exposure and suitable tracer selection, unlike simply sending an X-ray beam through the body.
Ultrasound uses reflected sound at tissue boundaries and no ionising radiation; it supports soft-tissue and foetal imaging but is limited by bone and gas and depends on the operator and suitable exposure controls.
An endoscope provides direct live views, sometimes sampling or treatment, using internal illumination and fibre optics or a camera. It is invasive and requires skilled use; fibreoptic versions use total internal reflection. Compare the clinical question, image information, invasiveness and exposure, not one universally 'best' method.
Use supplied comparison data for image clarity and time taken, and distinguish live video from still images and 2D from reconstructed 3D. Ultrasound often supplies live images; CT combines cross-sectional images, while a gamma image maps tracer distribution. CT and gamma methods involve ionising radiation and possible cell mutation; ultrasound does not use ionising radiation, but no method is automatically suitable for every examination.
In plain language
Light can be reflected, absorbed or transmitted. Which wavelengths reach your eyes determines colour. Refraction changes propagation when wave speed changes; a ray along the normal does not bend. Different imaging methods use transmitted X-rays, radiation from a tracer, reflected ultrasound or light inside an endoscope.
Self-check
Why does a blue object appear blue under white light?
Show the answer
It reflects blue wavelengths more strongly and absorbs much of the other visible light. In the ideal school model it reflects blue and absorbs the other colours; real reflectance is not necessarily one perfectly narrow band.
View diagrams
Reflection, refraction and total internal reflection
Rays show equal reflection angles, refraction towards the normal in a slower medium, and total internal reflection from an optically denser medium above its critical angle. Plane wavefronts are perpendicular to the rays and closer together in the slower medium.
Compare rays and perpendicular plane wavefronts. Angles are measured from the normal, not from the boundary.

Electrical Circuits and Ohm's LawCore
Scope: Core · Topic 6.3 (core)
Open revision guidance
What to know
Circuit symbols include: battery (two or more cells), power supply, switch, lamp, ammeter, voltmeter, resistor, variable resistor, buzzer, thermistor, solar cell, LED, and LDR.
In a series circuit, current is constant (I_total = I_1 = I_2) and supply voltage is shared (V_total = V_1 + V_2).
In a parallel circuit, voltage is the same across whole branches (V_total = V_branch1 = V_branch2) and currents sum to the supply (I_total = I_1 + I_2).
Adding resistors in series increases total resistance (R = R1 + R2).
Adding resistors in parallel decreases total resistance.
Use I = V/R with current in A, voltage in V and resistance in Ω. Ohm's law's proportional relationship applies to constant resistance under unchanged physical conditions; V/I can change for non-ohmic components.
With constant resistance, current is proportional to voltage; with constant voltage, increasing resistance decreases current. For an ohmic conductor keep temperature constant when interpreting a straight I–V graph. Example: a supplied 10 Ω resistor at 2 V gives 0.20 A and at 4 V gives 0.40 A; the doubled voltage doubles current.
Use given data to establish how resistance changes with temperature or illumination; recalling a particular response is not required here. The illustrative thermistor data below describe an NTC device, not every kind of thermistor. Variable resistors change by adjustment. Current also depends on supply and the rest of the circuit, not just one component.
What to do in an assessment
Connect an ammeter in series and a voltmeter in parallel to measure current and voltage.
Draw standard symbols connected by wires as a complete circuit, placing the ammeter in the route whose current is measured and the voltmeter across the component whose voltage is measured. Label meter units A and V.
Calculate total series resistance using R = R1 + R2.
Use the supplied equation I = V/R to calculate current from voltage and resistance. When resistance is requested in an introductory calculation, use the provided form R = V/I.
Use only the teacher's low-voltage supply; switch off while changing connections, choose suitable meter ranges and never connect an ammeter directly across the supply. LEDs need correct polarity and appropriate current limiting.
A switch in the common supply path controls every branch; a switch in one parallel branch controls that branch only. In series, an open switch breaks the single complete route.
For an LDR investigation, keep supply and other resistances constant, vary illumination and record current and voltage; use the provided relation R = V/I. Avoid changing temperature at the same time. For a thermistor investigation, use controlled temperatures without wetting electrical connections and allow readings to stabilise.
Interpret given data rather than assuming a temperature or light response. Constructed thermistor measurements: at 10, 20 and 30 °C, the voltage across the component is 3.0 V and the respective currents are 0.0010, 0.0020 and 0.0030 A. Using the supplied R = V/I gives 3000, 1500 and 1000 Ω: this particular thermistor's resistance decreases as temperature rises. These are illustrative readings, not collected measurements.
Constructed LDR measurements: at low, medium and high illumination the component voltage is 3.0 V and the respective currents are 0.0005, 0.0010 and 0.0015 A. The supplied R = V/I gives 6000, 3000 and 2000 Ω. The given results show falling resistance with increasing light; temperature and other conditions must not also change.
In a wire-wound variable resistor, a slider changes the length of resistive wire in use; other designs may differ. Test adjustment with the same low-voltage circuit. Compare solar-cell output under controlled illumination and LED/lamp behaviour with appropriate protection.
Worked series voltage balance: a 6 V supply with measured component drops of 2 V and 4 V gives 2 + 4 = 6 V. Worked parallel current balance: 0.20 A and 0.30 A branches require 0.50 A in the supply path; each branch has the same supply voltage.
In plain language
Electrical circuits use standard symbols to show how components like lamps and resistors are connected. In series, electricity follows one path, sharing voltage but maintaining the same current. In parallel, electricity branches off; each path receives the full supply voltage, but the total current is divided between them. Ohm’s Law allows us to calculate how much current flows based on voltage and resistance. Some components, like LDRs and thermistors, change their resistance automatically in response to the environment (light or heat), which changes the current flowing through them.
Self-check
If two 10-ohm resistors are connected in series to a 6V power supply, what is the total resistance and the current in the circuit?
Show the answer
Total resistance = 10 + 10 = 20 ohms. Current (I) = V / R = 6 / 20 = 0.3 Amperes.
View diagrams
Battery of cells
Power supply
Switch
Lamp
Ammeter
Voltmeter
Fixed resistor
Variable resistor
Buzzer
Thermistor
Solar cell
Light-emitting diode
Light-dependent resistor
The thirteen components named in outcome 6.3.1. Incoming light arrows identify the solar cell; outgoing light arrows identify the LED.
Worked d.c. measuring circuit
A complete constructed 6.0 V d.c. loop has a 3.0 Ω resistor, closed switch and ideal ammeter in series. An ideal voltmeter is connected only across the resistor. The ideal readings are 2.0 A and 6.0 V, found from I = V/R = 6.0/3.0 = 2.0 A; these are not measured values.
Constructed ideal circuit: an ammeter measures current in series and a voltmeter measures potential difference across the resistor in parallel.

Work Done and Energy TransferCore
Scope: Core · Topic 6.4 (core)
Open revision guidance
What to know
Work is defined as the energy transferred when a force causes an object to move in the direction of the force.
Work done measures the amount of energy moved from one store to another.
Frictional forces perform work that results in energy being dissipated (transferred to a less useful store, typically thermal energy), reducing useful energy transfer.
The work done is calculated using the equation: Work Done (Joules) = Force (Newtons) × Distance (meters) [W = Fd].
What to do in an assessment
To calculate work done: Multiply the magnitude of the force applied in the direction of motion by the displacement.
Example: A force of 50 N pushes a box 3 m across a floor. Work done = 50 N × 3 m = 150 J.
If there is no movement in the force's direction, that force does no mechanical work on the object: holding a stationary load is an example, even though the person's body uses energy. This course does not require resolving an angled force into components.
In plain language
Work measures energy transferred by a force acting through a distance in its direction. It need not come from a person's energy store: motors and gravity can do work too. Friction transfers energy into thermal stores, often reducing the useful mechanical transfer without destroying energy.
Self-check
If you push a crate with a force of 20 N for a distance of 5 m, how much work have you done?
Show the answer
Work done = 20 N × 5 m = 100 J.

Gravitational and Kinetic Energy CalculationsHigher
Scope: Higher · Unit 6 tier: Higher · Topic 6.4 (higher)
Open revision guidance
What to know
Change in Gravitational Potential Energy (ΔPE) is calculated by: ΔPE = mass × gravitational field strength × change in height (ΔPE = mgΔh).
Kinetic Energy (KE) is calculated by: KE = ½ × mass × speed squared (KE = ½mv²).
For ΔPE use mass in kg, g in N/kg and vertical height change in m. Use 10 N/kg for this specification's given Earth approximation unless another value is supplied.
In the KE formula, mass is in kilograms (kg) and speed (v) is in meters per second (m/s).
What to do in an assessment
Calculate ΔPE using the question's g, or the specification's approximate Earth value 10 N/kg. A 2 kg ball raised by 3 m gains 2 × 10 × 3 = 60 J. Use vertical height change, not distance along a sloping path.
Calculate KE: square the speed first, then multiply by mass and 0.5. Example: a 10 kg object moving at 4 m/s has KE = 0.5 × 10 × 16 = 80 J.
Link work and energy: a constructed 1000 kg vehicle at 20 m/s has KE = ½ × 1000 × 20² = 200 000 J. If it stops over 50 m on a level road and all this kinetic-energy decrease is accounted for by a mean opposing force, substitute into W = Fd: 200 000 = F × 50, then F = 4000 N. State the assumptions rather than assuming every braking situation has the same force.
In plain language
Calculate changes in gravitational energy from mass, gravitational field strength and vertical height change, and kinetic energy from mass and speed. Use the question's values and assumptions; the chosen reference height matters for gravitational energy.
Self-check
What is the kinetic energy of a 5 kg object travelling at 6 m/s?
Show the answer
KE = ½ × 5 kg × (6 m/s)² = 0.5 × 5 × 36 = 90 J.

Magnetic Fields, Electromagnetism, and InductionCore
Scope: Core · Topic 6.5 (core)
Open revision guidance
What to know
Outside a bar magnet, field lines run north to south; they form closed loops and do not cross. Straight-wire fields are concentric circles; a solenoid has a bar-magnet-like external field and a more uniform internal field. Closer drawn field lines represent a stronger field.
An electromagnet consists of a coil of wire wrapped around an iron core; its strength increases with current, number of turns, and presence of a soft iron core.
Moving a conductor so it cuts magnetic field lines induces voltage; current flows if there is a complete conducting circuit.
A current-carrying conductor crossing a magnetic field and the magnet exert forces on one another. The force is greatest for perpendicular current and field, as in this course's examples; a parallel wire has no such force. Greater current, stronger field or more wire in the field increases the force with other conditions fixed; no quantitative magnetic-force formula is required.
More secondary than primary turns gives step-up voltage; fewer gives step-down. The quantitative turns equation and the induction explanation of transformer operation are Higher.
The National Grid uses transformers to minimise energy loss by stepping up voltage for transmission and stepping down for consumption, using P = V x I.
What to do in an assessment
Sketch magnetic field lines for a bar magnet showing the North pole to South pole direction.
Calculate National Grid currents using P = V x I.
For comparable transferred power, step-up transformers increase voltage and reduce current for transmission; step-down transformers reduce voltage before suitable supplies reach users. This does not create extra power.
Constructed Grid comparison: P = 1 000 000 W and V = 100 000 V give I = P/V = 10 A. At 10 000 V for the same power, I = 100 A. Lower transmission current reduces heating losses in comparable wires.
For straight-wire field direction, the right-hand grip uses thumb along conventional current and curled fingers along the circular field. Around a solenoid, curl fingers with current and the thumb indicates its north end. This grip is different from Higher Fleming three-finger rules.
To strengthen an electromagnet, increase coil turns, current or use a suitable iron core, within the approved low-voltage equipment's limits. Electromagnets can be switched for relays, cranes and other actuators; switching off removes most of a soft-iron core's magnetism.
Induction increases with faster cutting of field lines, a stronger field or more coil turns, for otherwise comparable conditions. Current requires a closed circuit and also depends on resistance. Reversing motion or field reverses the induced direction.
In an a.c. generator, a coil rotates in a magnetic field; the induced direction reverses every half-turn. Slip rings and brushes connect the rotating coil without reversing its external connections. Faster rotation, stronger field or more turns increase output under comparable conditions.
Read output graphs against time: faster generator rotation increases frequency (shorter period) and peak output. More turns or a stronger field increase peak output without changing frequency if rotation speed stays fixed. Current amplitude also depends on the connected circuit.
An a.c. graph alternates above and below zero, representing reversed current direction. A steady d.c. example is a horizontal line on one side of zero. Direct current need not always have an unchanging magnitude: its defining difference here is that it does not reverse direction.
In a d.c. motor, forces on opposite sides of a current-carrying coil turn it. Brushes and a split-ring commutator reverse the coil current each half-turn so torque continues in the same rotational direction. Greater current, field or turns gives greater turning effect with other conditions controlled.
Induction is used in wind-turbine generators and regenerative braking in some hybrid vehicles. A.c. changes direction repeatedly; d.c. flows in one direction. The Grid responds to demand by adjusting generation, storage and transfers rather than supplying an unlimited fixed output.
In plain language
Moving a conductor across a magnetic field can induce a voltage and, in a complete circuit, current. A generator transfers energy from mechanical motion electrically; a motor does the reverse. Transformers change voltage to help transmit electricity with lower losses.
Self-check
A transformer has 100 primary turns and 500 secondary turns. Is it step-up or step-down?
Show the answer
Step-up: the secondary has more turns, so output voltage is greater than input. Calculating its numerical voltage using the turns equation is Higher.
View diagrams
Magnetic field pattern of a bar magnet
A bar-magnet field pattern has outside lines directed from north to south and an internal return direction from south to north. The lines form closed loops, do not cross, and their schematic spacing indicates relative field strength rather than measured values.
Magnetic fields around a straight wire and a solenoid
For current out of the page, the straight-wire field is anticlockwise. The solenoid section shows outward current above and inward current below, giving a field to the right inside and back to the left outside.
The three field patterns named in outcome 6.5.1: bar magnet, conducting wire and solenoid.

Higher Principles: Fleming's Rules and Transformer OperationHigher
Scope: Higher · Unit 6 tier: Higher · Topic 6.5 (higher)
Open revision guidance
What to know
Fleming's Right-Hand Rule: Thumb represents motion, first finger magnetic field, second finger induced current.
Fleming's Left-Hand Rule: Thumb represents force, first finger magnetic field, second finger current.
D.C. motor operation relies on the force exerted on a current-carrying coil in a magnetic field causing rotation.
Transformers operate by electromagnetic induction; an alternating current in the primary coil creates a changing magnetic field in the iron core, which induces an alternating voltage in the secondary coil.
A steady d.c. input does not provide the continually changing field needed for normal transformer operation. An ideal transformer conserves transferred power, while real transformers have losses.
What to do in an assessment
Use Fleming's Right-Hand Rule to predict induced conventional current: with field from left to right and a perpendicular conductor moving upwards, current is into the page. Reverse the motion and the predicted current reverses.
Use Fleming's Left-Hand Rule to predict motor force: with field left to right and conventional current out of the page, the force is upwards. Keep thumb, first finger and second finger mutually perpendicular.
Apply Fleming's rules to given directions, keeping conventional current distinct from electron flow; generator and motor operation and their qualitative output factors are common content.
For an ideal transformer, V₁/V₂ = N₁/N₂. With 100 primary turns, 500 secondary turns and input 230 V, V₂ = 230 × 500/100 = 1150 V. This is a theoretical calculation, not an instruction to operate mains equipment.
In plain language
Higher level physics focuses on the specific directions of forces and currents using hand rules. Motors use current to force rotation, while transformers use changing magnetic fields (induction) to transfer energy between coils.
Self-check
In Fleming's Left-Hand Rule, what do the thumb, first finger, and second finger represent?
Show the answer
Thumb: Force/Motion; First finger: Magnetic Field; Second finger: Current.
View diagrams
Generator effect: motion, field and induced current directions
Motor effect: current, field and force directions
Higher: distinguish the generator right-hand rule from the motor left-hand rule. Use conventional current; dots point out of the page and crosses into it.

Evidence for the Big Bang ModelCore
Scope: Core · Topic 6.6 (core)
Open revision guidance
What to know
Distant galaxies generally show redshift in their absorption spectra. This supports an expanding-Universe model; nearby individual stars and galaxies need not all be redshifted.
The Cosmic Microwave Background Radiation (CMBR) consists of redshifted radiation left over from the Big Bang.
Both cosmological redshift and CMBR provide primary evidence for the Big Bang model of the origin of the Universe.
What to do in an assessment
Compare a star's absorption spectrum to known gas spectra to identify elements.
Identify elements by matching absorption line positions (black lines) to reference patterns.
Qualitatively interpret galaxy motion; a shift of spectral lines toward the red end of the visible spectrum (longer wavelengths) indicates the source is moving away.
Compare relative positions and motions of galaxies using the magnitude of the shift.
Constructed element-matching example: known gas A has lines at positions 2, 5 and 8 on a supplied unshifted scale; gas B has 3 and 7. A sample with 2, 3, 5, 7 and 8 is consistent with both gases. Use the whole pattern, not just one coinciding line.
For equivalent line patterns, a shift towards red indicates recession and towards blue approach. In the usual distant-galaxy comparison model, a larger redshift indicates faster recession and generally greater separation; local motions can differ. Compare the same spectral features on the same scale.
In plain language
Compare absorption-line patterns with known gases to identify elements. Redshift and the Cosmic Microwave Background support the Big Bang model; they are scientific evidence, not a claim that every star is moving away. Qualitative spectrum comparisons are common content; the mechanism of cosmological wavelength stretching is Higher.
Self-check
How does the observation of an absorption spectrum allow us to determine the relative motion of a distant galaxy?
Show the answer
Match equivalent absorption-line patterns against the same wavelength scale. A shift to longer wavelengths is redshift and indicates recession in the distant-galaxy comparison model; a larger shift generally means faster recession and greater distance. The expansion mechanism is Higher, and local motions can differ.
View diagrams
Comparing hypothetical absorption-line patterns
Hypothetical line patterns only, not measurements of named elements. Gas A has lines at 450, 500 and 600 nm; gas B at 480 and 550 nm; the mixture contains their union. Two comparison spectra show the A pattern at proportionally redshifted wavelengths. Match equivalent features and compare the greater shift qualitatively; this does not state an expansion mechanism, a distance law, or that every object follows the same pattern.
Constructed absorption spectra, not measured or named-element data. Match whole patterns on the same wavelength scale, then compare equivalent redshifted features.

Cosmological Redshift and Universal ExpansionHigher
Scope: Higher · Unit 6 tier: Higher · Topic 6.6 (higher)
Open revision guidance
What to know
Cosmological redshift is not just due to velocity through space, but due to the actual expansion of the space between galaxies.
As the Universe expands, the wavelength of light travelling through it is stretched proportionally to the scale factor of the Universe.
The increase in redshift with distance is a direct consequence of the expansion of the Universe since the light was originally emitted.
This phenomenon provides quantitative evidence that the Universe began from a high-density, high-temperature state.
What to do in an assessment
Explain qualitatively why more distant galaxies generally show greater cosmological redshift; this specification does not require inventing an unprovided numerical distance formula.
Describe the relationship between cosmological expansion and the stretching of light waves.
Explain the mechanism of cosmological redshift as distinct from the standard Doppler effect.
In plain language
Cosmological redshift results from expansion during light's journey, increasing its wavelength as the scale of the Universe grows. This differs from an ordinary Doppler shift caused by local relative motion. The distance–redshift pattern, together with the CMB, supports a hotter, denser early Universe.
Self-check
What is the physical cause of cosmological redshift as opposed to a simple Doppler effect?
Show the answer
Cosmological redshift occurs because the expansion of the Universe stretches the space through which light travels, thereby increasing the wavelength of the light photons, whereas a Doppler effect is caused by the relative motion of an object through space.

Scientific Enquiry FrameworkCore
Scope: Core · shared-enquiry; core
Open revision guidance
What to know
The independent variable is changed; the dependent variable is measured; controlled variables are kept constant. A control experiment provides a comparison with the independent variable absent or fixed.
A hypothesis is a testable explanation which may be supported or contradicted. Experimental validity means that the method answers the question; a valid conclusion is supported by the results.
Range identifies the lowest and highest values tested. Resolution is the smallest change an instrument can distinguish. An anomaly is markedly different from the other results.
The true value is the result in ideal conditions; measurement error is the difference between a reading and that value. An inaccurate reading is far from the true value.
Accuracy, precision, repeatability and reproducibility describe different aspects of data quality; precise results are not necessarily accurate.
Random errors cause unpredictable variation; systematic errors consistently shift readings. Repeats reduce random error but not systematic error.
Hazards, risks and control measures must be distinguished. Consider perceived risk alongside evidence about likelihood and consequences.
Scientific models have limitations, develop with evidence and are checked through peer review and clear communication.
Primary data are observations or measurements you collect; secondary data were collected by someone else. Evaluate a secondary source's methods and evidence, not just whether its conclusion agrees with yours. Check who produced it, when, its purpose and any relevant conflicts of interest.
Constructed comparison, not a published experiment: one group measures oxygen production rates of 0.8 and 1.2 cm³ per minute at two light settings. A second group's recorded rates at those settings are 0.9 and 1.3 cm³ per minute. Both show an increase of 0.4 cm³ per minute, but the second group's values are each 0.1 higher. Check plant size, temperature, carbon dioxide, apparatus calibration and measurement uncertainty before deciding whether the results disagree. Do not combine differently controlled experiments into a mean without justification.
Science can test predictions and estimate consequences, but cannot by itself decide which ethical priorities society should choose. For example, evidence about a fuel's emissions and cost informs a decision, while fairness and acceptable environmental harm also involve values.
What to do in an assessment
Turn a scientific explanation into a testable hypothesis and identify the independent, dependent and controlled variables.
Explain why the apparatus, sampling method, range, repeats and control experiment suit the question.
Record observations with units; translate between tables, calculations, diagrams and graphs.
Use evidence to draw a valid conclusion, discuss uncertainty and explain any anomalies.
Evaluate personal, social, economic and environmental implications, practical risks and ethical limitations; communicate a reasoned decision.
Explain a specific method improvement and a follow-up investigation rather than simply saying 'make it more accurate'.
For secondary data, record the original source and date, identify how the measurements were obtained, and check units, sample size, conditions and uncertainty before comparing datasets.
Choose a presentation suited to the question: a table preserves numerical readings, a graph shows relationships, and a labelled diagram explains an apparatus or structure. Describe the spread of repeated readings, not just their mean.
In plain language
A scientific enquiry tests an explanation against evidence. Start with a question, use scientific knowledge to predict what should happen, and choose a method that can answer that question. For example, predict that increasing light intensity increases a pondweed's photosynthesis rate. Change light intensity, measure oxygen produced in a fixed time and keep plant size, temperature and carbon dioxide supply constant. A control experiment, such as a comparison in darkness with other conditions unchanged, helps show whether light caused the difference. Choose apparatus with suitable resolution: a ruler marked every millimetre cannot distinguish changes smaller than one millimetre. Check that equipment is set up correctly and calibrated. Use representative samples rather than choosing only convenient organisms or results. Record units, the range of values tested and repeats in a table before plotting or calculating. An unusual reading is an anomaly: investigate and explain it rather than silently deleting it. Precision means little spread between readings; accuracy means closeness to the true value. Readings of 21.0, 21.1 and 21.0 degrees Celsius are precise, but inaccurate if a calibrated reference reads 19.0. A systematic offset remains when measurements are repeated; correct or replace the faulty apparatus. Random variation can be reduced by repeats and a mean. Repeatability concerns the same learner or group repeating the method; reproducibility concerns other learners or groups obtaining similar results. Uncertainty expresses the interval in which the true value is expected, such as 20 ± 2 degrees Celsius. Use the uncertainty formula supplied in an assessment rather than assuming a formula is always required from memory. A valid conclusion is supported by the collected evidence and a method suited to the question. Explain patterns, compare primary measurements with trustworthy secondary data and distinguish an association from proof of a cause. Suggest a specific improvement and say why it would help, for example collecting oxygen volume rather than counting bubbles of unequal size. Communicate the question, method, results and limitations so others can check the work. Peer review means other scientists critically examine methods and conclusions; new evidence can lead to changes in models and theories. Evaluate practical and wider risks using both likelihood and consequences. A hazard is something capable of harm; risk concerns the step where harm could occur; a control measure reduces that risk. For example, an irritant solution is a hazard, splashing during transfer is a risk, and eye protection and a supervised safe transfer method are controls. Follow your teacher's risk assessment; this guide is not permission to perform experiments at home. Scientific evidence can inform choices about health, costs and environmental effects, but ethical questions and people's values also matter.
Self-check
How do random and systematic errors differ, and why will repeating measurements not correct a systematic error?
Show the answer
Random errors vary unpredictably; repeats and a mean reduce their effect. A systematic error consistently shifts readings, for example a balance with a zero error. Repeating that faulty measurement does not remove the offset.
Essential Mathematical Skills in ScienceCore
Scope: Core · shared-maths; core
Open revision guidance
What to know
Decimal numbers, SI prefixes, unit conversions, ratios, fractions, percentages, significant figures, arithmetic means, probability and estimates are tools for interpreting scientific evidence.
A table or graph must communicate quantities and units, not only a pattern.
Substitution requires consistent units; a physical answer includes its unit.
For a square of side a: area = a². For a rectangle: area = length × width. For a triangle: area = base × perpendicular height/2.
For a circle: area = πr² and circumference = 2πr. For a cube: volume = a³ and surface area = 6a².
Recognise quantities and their units: length m, mass kg, time s, current A, speed m/s, force N, energy J, power W, voltage V and resistance Ω. A prefix changes the size of the unit: 1 kW = 1000 W and 1 mA = 0.001 A.
Because 1 cm = 0.01 m, 1 cm² = 0.0001 m² and 1 cm³ = 0.000001 m³. Do not use the length conversion factor unchanged for an area or volume.
The specification says the Unit 2 and Unit 5 papers include a periodic table on their final page, and the Unit 3 and Unit 6 papers include equations on page 2. Practise selecting and using the relevant information. This does not mean every equation used in every science paper is supplied, or promise an additional 2028 formula aid.
What to do in an assessment
Convert SI units and prefixes, including the different factors for lengths, areas and volumes.
Calculate ratios, fractions, percentages, probabilities and arithmetic means; check decimal answers against an order-of-magnitude estimate.
Construct and interpret tables, diagrams and experimental graphs, identifying axes, units, scales and patterns.
Substitute numerical values into equations with appropriate units and round final answers sensibly.
Calculate areas, circumference, cube surface area and cube volume; use angular measures in degrees.
In plain language
Use numbers with their units. Kilo means 1000 times the base unit, centi means one hundredth, milli means one thousandth and micro means one millionth. Thus 2500 milligrams = 2.5 grams and 3 centimetres = 0.03 metres. Area and volume conversions require squaring or cubing the length conversion: 1 cubic centimetre = 0.000001 cubic metres. Keep extra digits during a calculation and round the final answer to a justified number of significant figures; 0.004567 to two significant figures is 0.0046. Ratios compare quantities in the same units: 6 red beads to 3 blue beads gives 2:1. Red beads are 6/9 = 2/3 of the sample, or about 66.7%. If one bead is selected at random, its probability of being blue is 3/9 = 1/3. The mean of readings 8, 10 and 12 is (8 + 10 + 12)/3 = 10. An order-of-magnitude estimate uses rounded values: 198 × 51 is approximately 200 × 50 = 10000, so an answer near 100 is implausible. Record experimental data in a table with a heading and unit for each quantity. Plot the independent variable on the horizontal axis and the dependent variable on the vertical axis, using a sensible scale. For the pairs (time in seconds, distance in metres) (0,0), (2,4), (4,8), points lie on a rising straight line: at 3 seconds the distance is 6 metres. Read scales carefully and use a suitable best-fit line or curve rather than joining points arbitrarily. Translate a graph back into numerical values before substituting them into an equation. Substitute with consistent units: speed = distance/time = 12 metres/3 seconds = 4 metres per second. State the physical meaning of the answer, not just a number. For geometry, a rectangle's area is length × width; a triangle's area is base × perpendicular height/2; a cube of side a has volume a³ and surface area 6a². A 2 centimetre cube therefore has volume 8 cubic centimetres and surface area 24 square centimetres. A circle of radius 3 centimetres has area πr² = 9π square centimetres and circumference 2πr = 6π centimetres. Use angles in degrees and measure them from the stated reference line, such as the normal in a reflection diagram.
Self-check
A rectangle is 5 centimetres long and 4 centimetres wide. What is its area, including its unit?
Show the answer
Area = length × width = 5 × 4 = 20 square centimetres. The unit is cm² because two lengths are multiplied.
Higher Tier Mathematical SkillsHigher
Scope: Higher · Higher in either Unit 1 tier or Unit 2 tier or Unit 3 tier or Unit 4 tier or Unit 5 tier or Unit 6 tier · shared-maths; higher
Open revision guidance
What to know
Standard form is A × 10ⁿ with 1 ≤ A < 10.
Changing the subject preserves equality by doing the same operation on both sides.
The equation y = mx + c describes a straight line: m is its gradient and c its vertical-axis intercept.
A gradient and intercept have meanings and units determined by the plotted quantities.
What to do in an assessment
Express large and small scientific quantities in standard form.
Rearrange an equation step by step and check the answer by substitution.
Higher circuit example, substituting before changing the subject: given I = V/R, I = 0.20 A and V = 6.0 V, write 0.20 = 6.0/R. Multiply both sides by R to give 0.20R = 6.0, then divide by 0.20: R = 30 Ω. Check that 6.0/30 = 0.20 A.
Calculate a linear graph's gradient using change in vertical quantity divided by change in horizontal quantity.
Interpret slope and intercept in the physical context, with units; distinguish an instantaneous tangent gradient from a mean rate.
In plain language
Standard form writes a number as A × 10ⁿ, with 1 ≤ A < 10. For example, 450000 = 4.5 × 10⁵ and 0.00032 = 3.2 × 10⁻⁴. The exponent tells you how many places the decimal point moves; a negative exponent denotes a small number. Change the subject of an equation by applying the same operation to both sides. From v = d/t, multiply both sides by t to get vt = d, then divide by v to obtain t = d/v. If d = 24 metres and v = 6 metres per second, t = 24/6 = 4 seconds. Check by substituting back: 6 = 24/4. For a straight line y = mx + c, m is the gradient and c the vertical-axis intercept. Choose two widely separated points on the best-fit line, not necessarily two measured points. For (2,7) and (6,19), gradient = (19 − 7)/(6 − 2) = 3, and c = 7 − 3 × 2 = 1, so y = 3x + 1. If y is distance in metres and x is time in seconds, the slope means 3 metres per second and the intercept means a starting distance of 1 metre. For reaction data, a tangent's gradient describes the rate at one instant; choose two points on that tangent. Do not confuse this with a mean rate over the whole experiment.
Self-check
In y = 3x + 2, what is the vertical-axis intercept, and how can you check it?
Show the answer
The intercept is 2. Substitute x = 0: y = 3 × 0 + 2 = 2.

Unit 7 Scientific Enquiry AssessmentPractical assessment guidanceCore
Scope: Core · unit-7; core
Reading this guidance does not complete practical assessment. It is not counted as written-exam progress.
Open revision guidance
What to know
Two enquiries are chosen from three; each has a one-hour practical task and one-hour written task.
Task 1: collaborative practical work, 6 marks per enquiry, groups of at most three learners.
Task 2: independent written work under high control, 22 marks per enquiry.
This external assessment is marked by WJEC, totals 56 marks and contributes 10%; it is not counted in written-exam checklist progress.
Unit 7 is not tiered. The Foundation/Higher revision toggle does not change its assessment arrangements or register you for an exam.
Your centre chooses the enquiries and manages the official assessment arrangements. Use only the materials and assistance permitted by your teacher; never submit another learner's analysis as your own.
What to do in an assessment
Use suitable apparatus, the approved safe method and clear data recording during Task 1.
Use Task 1 evidence to produce your own analysis and evaluation in Task 2.
Apply the scientific enquiry framework and terminology to explain the quality and limitations of the evidence.
In plain language
Unit 7 is an external Scientific Enquiry assessment marked by WJEC, not another topic to tick as completed written-exam revision. Complete two enquiries from the three available. Each has a one-hour practical task worth 6 marks and a one-hour independent written task worth 22 marks: 28 marks per enquiry and 56 altogether. The unit contributes 10% of the qualification and is first available in spring 2028. For the practical task, work in a group of no more than three learners and record your own observations and measurements. The subsequent written task is completed independently under high control: use the evidence to analyse, explain and evaluate, without help from your group. Your teacher organises the assessment and its controls. Practise the enquiry skills above, but do not treat a tick in this guide as proof that the assessed tasks have been completed.
Self-check
How many marks are available across both enquiries, and may the group produce a shared answer for Task 2?
Show the answer
Each enquiry has 6 practical + 22 written = 28 marks. Two enquiries give 2 × 28 = 56 marks. Task 2 is independent, not a group answer.

Previous revision ticks

These are your ticks from the earlier guide. They do not count towards the new lessons, and the old content is not current teaching.

Earlier revision tick: Cells and transport
Cells and transport
Earlier revision tick: Active Transport Supplement
Active Transport Supplement
Earlier revision tick: Enzymes, Respiration, and Photosynthesis
Enzymes, Respiration, and Photosynthesis
Earlier revision tick: Advanced Energy Systems and Limiting Factors
Advanced Energy Systems and Limiting Factors
Earlier revision tick: Plant transport and human body systems
Plant Transport Systems
Earlier revision tick: Mineral uptake
Mineral uptake
Earlier revision tick: Energy Transfer and Ecosystem Interactions
Energy Transfer and Ecosystem Interactions
Earlier revision tick: Atomic Structure and Chemical Calculations
Atomic Structure and Chemical Calculations
Earlier revision tick: Moles and Avogadro's Number
Moles and Avogadro's Number
Earlier revision tick: Structure and Properties of Elements
Structure and Properties of Elements
Earlier revision tick: Trends in Group Reactivity
Trends in Group Reactivity
Earlier revision tick: Chemical Reactions, Rates, and Catalysts
Chemical Reactions, Rates, and Catalysts
Earlier revision tick: Higher Supplement: Rate Calculation from Graphs
Higher Supplement: Rate Calculation from Graphs
Earlier revision tick: Earth's Resources and Atmospheric Change
Earth's Resources and Atmospheric Change
Earlier revision tick: Higher Concepts: Climate Feedback Loops
Higher Concepts: Climate Feedback Loops
Earlier revision tick: Motion, Graphs, and Stopping Distances
Motion, Graphs, and Stopping Distances
Earlier revision tick: Advanced Motion Graphs (Higher)
Advanced Motion Graphs (Higher)
Earlier revision tick: Energy Principles, Efficiency, and Power
Energy Principles, Efficiency, and Power
Earlier revision tick: Forces, Newton's Laws, and Terminal Speed
Forces, Newton's Laws, and Terminal Speed
Earlier revision tick: Advanced Applications of Newton's Laws
Advanced Applications of Newton's Laws
Earlier revision tick: Wave Properties and the Electromagnetic Spectrum
Wave Properties and the Electromagnetic Spectrum
Earlier revision tick: The Solar System, Observations, and Star Life Cycles
The Solar System, Observations, and Star Life Cycles
Earlier revision tick: Higher Physics: Stellar Equilibrium Dynamics
Higher Physics: Stellar Equilibrium Dynamics
Earlier revision tick: Human Impact on Ecosystems
Human Impact on Ecosystems
Earlier revision tick: DNA Structure and Function
DNA Structure and Function
Earlier revision tick: Protein Synthesis and Control
Protein Synthesis and Control
Earlier revision tick: Variation, Natural Selection, and Gene Technology
Variation, Natural Selection, and Gene Technology
Earlier revision tick: Higher Concepts in Variation and Ethics
Higher Concepts in Variation and Ethics
Earlier revision tick: The Nervous System and Reflex Actions
The Nervous System and Reflex Actions
Earlier revision tick: Higher Reflex Arc Mechanisms
Higher Reflex Arc Mechanisms
Earlier revision tick: Disease and Human Defence Systems
Disease and Human Defence Systems
Earlier revision tick: Higher Immunity: Memory Cells
Higher Immunity: Memory Cells
Earlier revision tick: Bonding, Structure, and Properties
Bonding, Structure, and Properties
Earlier revision tick: Advanced Covalent Bonding
Advanced Covalent Bonding
Earlier revision tick: Acids, Bases, and Salt Identification
Acids, Bases, and Salt Identification
Earlier revision tick: Higher Level Identification of Metal Ions
Higher Level Identification of Metal Ions
Earlier revision tick: Reactivity of Metals and Extraction Principles
Reactivity of Metals and Extraction Principles
Earlier revision tick: Advanced Redox and Calculations
Advanced Redox and Calculations
Earlier revision tick: Introduction to Alkanes and Alkenes
Introduction to Alkanes and Alkenes
Earlier revision tick: Higher Supplement: Isomerism and Addition Products
Higher Supplement: Isomerism and Addition Products
Earlier revision tick: Fundamentals of Radioactive Decay and Half-life
Fundamentals of Radioactive Decay and Half-life
Earlier revision tick: Advanced Decay Equations and Kinetics
Advanced Decay Equations and Kinetics
Earlier revision tick: Wave Behaviour and Medical Imaging
Wave Behaviour and Medical Imaging
Earlier revision tick: Electrical Circuits and Ohm's Law
Electrical Circuits and Ohm's Law
Earlier revision tick: Work Done and Energy Transfer
Work Done and Energy Transfer
Earlier revision tick: Gravitational and Kinetic Energy Calculations
Gravitational and Kinetic Energy Calculations
Earlier revision tick: Magnetic Fields, Electromagnetism, and Induction
Magnetic Fields, Electromagnetism, and Induction
Earlier revision tick: Higher Principles: Fleming's Rules and Transformer Operation
Higher Principles: Fleming's Rules and Transformer Operation
Earlier revision tick: Evidence for the Big Bang Model
Evidence for the Big Bang Model
Earlier revision tick: Cosmological Redshift and Universal Expansion
Cosmological Redshift and Universal Expansion
Earlier revision tick: Scientific Enquiry Framework
Scientific Enquiry Framework
Earlier revision tick: Essential Mathematical Skills in Science
Essential Mathematical Skills in Science
Earlier revision tick: Higher Tier Mathematical Skills
Higher Tier Mathematical Skills

How OmniStudy helps you revise

Answer exam-style questions on any topic below and get marked in seconds, with feedback on how to win more marks.
Flashcards, quizzes and revision games generated for every topic.
Practise real past papers with mark schemes.
A study planner with an exam countdown, built around your weakest topics.
Everything works in English and Welsh.

This guide is also available in Welsh (Cymraeg): Welsh (Cymraeg) guide

Ready to start?

Free to start. Pick your subject, answer a question, and see your first mark in minutes.

Start revising free

Revision points, with the explanation beside them

Unit 1 tier

Unit 2 tier

Unit 3 tier

Unit 4 tier

Unit 5 tier

Unit 6 tier

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know

What to do in an assessment

In plain language

Self-check

What to know