Physics Revision: WJEC GCSE Science (Double Award) · teaching from 2016
This guide is for the legacy qualification taught from 2016. The page shows Physics requirements plus shared skills and Unit 7; choose another science above to switch scope.
Qualification code: 60182362
Course details
Assessment Six 75-minute, 60-mark written exams, each worth 15%, plus Unit 7 Practical Assessment worth 10%; summer 2027 is the final full assessment, with a January 2028 resit subject to demand.
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Reviewed course guidance
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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.
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Topic group
Unit 3 · 3.1 · Electrical Circuits and Power
- Core
Scope: Core · Topic 3.1 (core)
Open revision guidance
What to know
- Circuit symbols: cell (parallel lines), switch (break in wire), lamp (cross in circle), voltmeter (V in circle), ammeter (A in circle), resistor (rectangle), variable resistor (rectangle with arrow), fuse (rectangle with wire through), LED (diode symbol with arrows), thermistor (resistor with hockey stick line), LDR (resistor in circle with light arrows), diode (triangle pointing to line).
- Series circuits: Current is identical throughout; total voltage of the supply is divided between components (V_total = V1 + V2 + ...).
- Parallel circuits: Voltage is identical across branches; current is split between branches (I_total = I1 + I2 + ...).
- Ohm's Law: V = I × R (Voltage in Volts, Current in Amperes, Resistance in Ohms).
- Adding components in series increases total resistance; in parallel decreases total resistance.
- Power: Energy transferred per unit time (E = P × t, where P is in Watts, E in Joules, t in seconds). Power = Voltage × Current (P = V × I).
What to do in an assessment
- Use an ammeter in series and a voltmeter in parallel to measure I and V.
- Construct I-V graphs: Ohmic resistors produce a straight line through the origin; filament lamps produce an S-curve due to resistance increasing with temperature; diodes show high resistance in reverse bias and low resistance in forward bias.
- Design experiments using variable resistors to control current/voltage for LDRs (light sensitive) and thermistors (heat sensitive).
In plain language
Electrical circuits use standard symbols to show how power flows. In series, electricity has only one path, sharing the supply voltage. In parallel, electricity branches off, sharing the current but keeping the same voltage. Resistance measures how hard it is for current to flow, related by Ohm's Law (V=IR). Adding more resistors in series makes the total resistance higher, but adding them in parallel provides more paths, lowering total resistance. Power tells us how fast energy is used, calculated as voltage times current.
Self-check
A circuit has a 12V supply and a 4-ohm resistor. What is the current in the circuit?
Show the answer
Using I = V / R, I = 12V / 4 ohms = 3 Amperes.
Topic group
Unit 3 · 3.1 · Advanced Circuit Calculations
- Higher
Scope: Higher · Unit 3 tier: Higher · Topic 3.1 (higher)
Open revision guidance
What to know
- Total resistance in series: R_total = R1 + R2.
- Total resistance in parallel: 1/R_total = 1/R1 + 1/R2.
- Power using resistance: P = I^2 × R.
What to do in an assessment
- Calculate total resistance for complex networks by breaking them into simpler series or parallel blocks.
- Worked mixed circuit: 6 Ω and 3 Ω in parallel give 1/R = 1/6 + 1/3 = 1/2, so R = 2 Ω. With 1 Ω in series on a 6 V supply, total R = 3 Ω and supply current = 2 A. The series resistor takes 2 V, leaving 4 V across each branch; branch currents 4/6 A and 4/3 A add to 2 A.
- Use P = I^2 × R to find power dissipation in resistors when voltage is unknown.
In plain language
Higher level circuit analysis allows us to solve for total resistance in any combination of series and parallel connections using simple addition or fraction rules. We also gain a useful formula for power, I-squared R, which directly calculates energy transfer in a component based on its current and resistance.
Self-check
Two 10-ohm resistors are in parallel. What is the total resistance?
Show the answer
1/R_total = 1/10 + 1/10 = 2/10. So R_total = 10/2 = 5 ohms.
Topic group
Unit 3 · 3.2 · Electricity Generation and Distribution
- Core
Scope: Core · Topic 3.2 (core)
Open revision guidance
What to know
- Renewable energy sources include hydroelectric, wind, wave, tidal, waste, crops, solar, and wood.
- Non-renewable energy sources include fossil fuels (coal, oil, gas) and nuclear fuel.
- Fuel-based power stations generate electricity by burning fuel to heat water into steam, which spins a turbine connected to a generator.
- Sankey diagrams represent energy transfers, showing input energy as the total width and useful output energy as the narrower width.
- Percentage Efficiency = (useful energy output / total energy input) × 100.
- The National Grid uses step-up transformers to increase voltage for efficient transmission (reducing heat loss in cables) and step-down transformers to decrease voltage for safe consumer use.
- Power calculation: P = V × I (Power in Watts = Volts × Amps).
- Comparison criteria: Efficiency, reliability, carbon footprint, and output.
What to do in an assessment
- Calculate efficiency: A coal power station inputs 500 MJ of chemical energy and outputs 150 MJ of electricity. Efficiency = (150 / 500) × 100 = 30%.
- Calculate power: A house appliance draws 10A at 230V. Power = 230V × 10A = 2300W.
- Construct a Sankey diagram identifying waste energy typically dissipated as heat.
In plain language
We generate electricity by converting different energy sources into rotational movement for generators. We use the National Grid to move this electricity across the country, using high voltage for travel to save energy and low voltage for safety in homes. Efficiency tells us how much of our original energy source actually turns into useful electricity.
Self-check
Why is the voltage stepped up for transmission in the National Grid?
Show the answer
Voltage is stepped up to reduce current for a given power level, which significantly reduces thermal energy loss in the transmission cables.
Topic group
Unit 3 · 3.3 · Energy Transfer and Domestic Efficiency
- Core
Scope: Core · Topic 3.3 (core)
Open revision guidance
What to know
- Thermal energy transfers from higher to lower temperatures via conduction, convection, and radiation.
- Density is calculated as mass divided by volume (ρ = m/V), measured in kg/m³.
- Solids have high density (particles packed), liquids medium, and gases low (particles far apart).
- Insulation methods like loft, cavity wall, double glazing, and draught excluders restrict energy loss.
- Payback time calculation: Total cost of insulation / annual savings.
What to do in an assessment
- Use the density equation to solve for missing variables.
- Evaluate insulation techniques using cost-benefit data.
- Calculate annual savings and payback periods for various energy-saving measures.
In plain language
Energy always moves from hot to cold areas. We can save energy and money by insulating our homes, which slows this transfer, and we can compare these methods using math to find how long it takes for the insulation to pay for itself.
Self-check
An insulation upgrade costs £600 and saves £150 in annual energy bills. What is the payback time?
Show the answer
4 years (£600 / £150).
Topic group
Unit 3 · 3.3 · Molecular Mechanisms of Heat Transfer
- Higher
Scope: Higher · Unit 3 tier: Higher · Topic 3.3 (higher)
Open revision guidance
What to know
- Conduction is the transfer of energy through molecular vibration/collisions.
- Metals are superior conductors because they contain free electrons that diffuse rapidly and collide with ions to transfer kinetic energy.
- Convection occurs in fluids because heating causes molecules to move apart, reducing density and causing the fluid to rise, while cooler, denser fluid descends.
What to do in an assessment
- Explain heat transfer using molecular and kinetic energy models.
- Describe how changes in volume and density drive convection currents.
In plain language
At the microscopic level, heat spreads because molecules bump into each other. In metals, tiny moving electrons help spread heat even faster. Convection works because hot fluids expand and get lighter, causing them to float upwards.
Self-check
Why do metals conduct heat better than non-metal solids?
Show the answer
Metals have free electrons that move quickly through the lattice, transferring kinetic energy to other ions more effectively than vibrating molecules alone.
Topic group
Unit 3 · 3.4 · Domestic Electricity and Energy Efficiency
- Core
Scope: Core · Topic 3.4 (core)
Open revision guidance
What to know
- Power is measured in kilowatts (kW) for convenience.
- Energy is measured in kilowatt hours (kWh).
- Units used (kWh) = Power (kW) × Time (h).
- Cost = Units used × Cost per unit.
- Data for appliance costs can be gathered from power ratings or energy labels (A-G).
- Direct Current (d.c.) flows in one direction; Alternating Current (a.c.) continuously reverses direction.
- Fuses melt to break a circuit if current is too high; MCBs (Miniature Circuit Breakers) detect overcurrent and trip, while RCCBs (Residual Current Circuit Breakers) detect differences in live/neutral current to prevent electric shock.
- A ring main is a circuit where the live, neutral, and earth wires return to the source to allow thinner wires to carry higher current; Live is brown/energized, Neutral is blue/completes circuit, Earth is green/yellow for safety.
- Payback time = Initial Cost / Annual Savings.
- Efficiency = (Useful Energy Output / Total Energy Input) × 100%.
What to do in an assessment
- Calculate the cost of a 2.5 kW heater used for 4 hours at £0.20 per kWh: (2.5 kW × 4 h) = 10 kWh. Cost = 10 kWh × £0.20 = £2.00.
- Select a fuse rating for a 230V, 3kW kettle using I = P/V: I = 3000 / 230 = 13.04A. A 13A fuse is required.
- Calculate payback for solar panels costing £4000 saving £500 annually: 4000 / 500 = 8 years.
In plain language
This topic covers how we measure, pay for, and use electricity safely in our homes. It includes understanding electrical circuits, safety devices like fuses and breakers, how much appliances cost to run, and the financial benefits of renewable energy.
Self-check
If an appliance uses 0.5 kW and runs for 10 hours at a price of £0.30 per kWh, what is the total cost?
Show the answer
0.5 kW × 10 h = 5 kWh. 5 kWh × £0.30 = £1.50.
Topic group
Unit 3 · 3.5 · Wave Properties and the Electromagnetic Spectrum
- Core
Scope: Core · Topic 3.5 (core)
Open revision guidance
What to know
- Transverse waves oscillate perpendicular to the direction of energy transfer; longitudinal waves oscillate parallel to it.
- Wave terminology: Amplitude (maximum displacement from equilibrium), Wavelength (distance between consecutive crests), Frequency (number of waves per second, in Hertz), and Wave speed (speed at which energy is transferred) [L19, L99].
- Wave equation: v = f × λ, where v is speed (m/s), f is frequency (Hz), and λ is wavelength (m).
- Refraction occurs when waves change speed and wavelength as they cross a boundary into a different medium.
- Electromagnetic (EM) spectrum regions: radio, microwave, infra-red, visible, ultraviolet, X-ray, gamma; all travel at the same speed (3.0 x 10^8 m/s) in a vacuum [L79, L82].
- Ionizing radiation (UV, X-rays, Gamma) transfers energy sufficient to detach electrons, damaging biological cells.
- Communication uses EM waves; satellites in geostationary orbit maintain constant position relative to Earth's surface [L89, L119].
What to do in an assessment
- Draw a transverse wave on a position-displacement graph, labelling amplitude from the centre to a peak, and wavelength as the distance between two successive peaks.
- Calculate wave speed using v = f × λ. Example: If a wave has a frequency of 50 Hz and a wavelength of 0.2 m, the speed is 50 × 0.2 = 10 m/s.
- Sketch plane wave fronts refracting at a boundary, showing a change in wavelength as the waves slow down or speed up [L39, L49].
In plain language
Waves are how energy moves. Transverse waves move up and down, while longitudinal waves move back and forth. All electromagnetic waves—from radio waves to gamma rays—travel at the same high speed in a vacuum, but they differ in frequency and wavelength. High-frequency waves like X-rays are ionizing, meaning they can break chemical bonds and damage cells.
Self-check
A wave has a frequency of 200 Hz and a wavelength of 1.5 m. Calculate its speed.
Show the answer
300 m/s (200 Hz × 1.5 m = 300 m/s).
View diagrams
Wave profile, wavefronts and frequencyCompare the diagram with the explanation, then use practice mode before opening the key.
Topic group
Unit 6 · 6.1 · Motion, Speed, and Stopping Distances
- Core
Scope: Core · Topic 6.1 (core)
Open revision guidance
What to know
- Speed is distance divided by time (units: m/s). Velocity is speed in a given direction.
- Acceleration is the rate of change of velocity (units: m/s²).
- Distance-time graphs: gradient = speed.
- Speed-time graphs: gradient = acceleration.
- Thinking distance is distance travelled during reaction time; braking distance is distance travelled while brakes are applied.
- Stopping distance = thinking distance + braking distance.
- Factors affecting distance: drugs, alcohol, tiredness (reaction time); brake condition, road surface, weather (braking distance).
What to do in an assessment
- Calculate speed: v = d/t. Example: A car travels 100m in 5s. Speed = 100/5 = 20 m/s.
- Calculate acceleration: a = (v - u) / t. Example: Car speeds from 0 to 20 m/s in 4s. a = 20/4 = 5 m/s².
- Use distance-time graphs to calculate speed by finding the slope of the line.
- Use speed-time graphs to identify constant speed, acceleration, and deceleration.
- Discuss traffic safety: Seat belts reduce force by increasing the time taken for the body to come to a halt (F = ma, reducing a). Speed limits reduce total stopping distance.
In plain language
This lesson covers how objects move and why vehicles need specific stopping distances. We learn to measure how fast something is moving, how it speeds up, and how we can use graphs to represent this movement. We also look at the safety rules for driving, like why thinking and braking distances matter when deciding on speed limits.
Self-check
If a car is travelling at 30 m/s and brakes to a stop in 5 seconds, what is its deceleration?
Show the answer
Acceleration = (final velocity − initial velocity)/time = (0 − 30)/5 = −6 m/s². The magnitude of the deceleration is 6 m/s².
Topic group
Unit 6 · 6.1 · Supplement: Velocity-Time Graphs and Displacement
- Higher
Scope: Higher · Unit 6 tier: Higher · Topic 6.1 (higher)
Open revision guidance
What to know
- In a velocity-time graph, the area under the line represents total displacement (distance travelled).
- For a constant acceleration (straight line slope), the distance is calculated as the area of the shape under the graph (e.g., triangle or trapezoid).
What to do in an assessment
- Calculate distance from a velocity-time graph. Example: If a car accelerates from 0 to 10 m/s over 5 seconds (forming a triangle), Distance = 0.5 * base * height = 0.5 * 5 * 10 = 25m.
In plain language
At the Higher level, you must be able to calculate exactly how far an object has travelled by measuring the area under a velocity-time graph, rather than just calculating the acceleration from the gradient.
Self-check
A vehicle moves at a constant velocity of 20 m/s for 10 seconds. Using a velocity-time graph approach, how far has it travelled?
Show the answer
The area under the graph is a rectangle: width 10s * height 20 m/s = 200m.
Topic group
Unit 6 · 6.2 · Newton's Laws of Motion, Mass, and Weight
- Core
Scope: Core · Topic 6.2 (core)
Open revision guidance
What to know
- Inertia is the tendency of an object to resist changes in its state of motion; mass is the measure of this resistance.
- Newton's First Law: An object remains at rest or moves at a constant velocity unless acted upon by an unbalanced force.
- Resultant forces cause acceleration: acceleration is directly proportional to force and inversely proportional to mass.
- Newton's Second Law: F = ma, where F is resultant force (Newtons), m is mass (kg), and a is acceleration (m/s²).
- Mass (kg) is the amount of matter; Weight (N) is the force of gravity on that mass (W = mg). On Earth, 1 kg ≈ 10 N.
- Terminal speed occurs when the upward resistive forces (like air resistance) on a falling object equal the downward force of gravity, resulting in zero acceleration.
- Newton's Third Law: When two objects interact, they exert equal and opposite forces on each other.
What to do in an assessment
- Calculate force using F = ma: If a 5 kg object accelerates at 2 m/s², F = 5 kg × 2 m/s² = 10 N.
- Calculate weight using W = mg: If g = 9.8 N/kg, an object of 2 kg has a weight of W = 2 kg × 9.8 N/kg = 19.6 N.
- Analyse free-body diagrams to determine if forces are balanced (constant velocity) or unbalanced (acceleration).
In plain language
Motion is governed by predictable rules. Things naturally keep doing what they are already doing (inertia). To change their speed or direction, you must apply an unbalanced force. Newton's laws allow us to calculate exactly how much force is needed based on the object's mass and how fast we want it to speed up. Finally, remember that mass stays the same everywhere, but weight changes depending on the gravitational pull of the planet you are on.
Self-check
A 10 kg box is pushed across a floor with a resultant force of 20 N. What is its acceleration?
Show the answer
Using F = ma, 20 N = 10 kg × a. Therefore, a = 20 / 10 = 2 m/s².
Topic group
Unit 6 · 6.2 · Level Statements of Newton's Laws
- Higher
Scope: Higher · Unit 6 tier: Higher · Topic 6.2 (higher)
Open revision guidance
What to know
- Higher level requires explicit stateability of all three laws.
- Newton's First Law: An object will remain at rest, or continue to move at a constant velocity, unless acted upon by an external resultant force [L21, L15].
- Newton's Second Law: The acceleration of an object is directly proportional to the resultant force applied and inversely proportional to its mass, stated as the equation F = ma [L43, L37].
- Newton's Third Law: For every action, there is an equal and opposite reaction; if object A exerts a force on object B, then object B exerts an equal and opposite force on object A [L75, L69].
What to do in an assessment
- Practice writing out the full formal definitions of these laws without omitting key terms like 'resultant', 'constant velocity', and 'equal and opposite'.
In plain language
At the Higher level, you must be precise with your definitions. It is not enough to understand the concepts; you must be able to state the formal laws clearly and accurately in an examination setting.
Self-check
State Newton's Third Law of Motion.
Show the answer
If object A exerts a force on object B, then object B exerts a force of equal magnitude and opposite direction on object A.
Topic group
Unit 6 · 6.3 · Energy, Work, and Mechanical Systems
- Core
Scope: Core · Topic 6.3 (core)
Open revision guidance
What to know
- Energy is transferred when a force acts on a moving body, but the total amount of energy remains constant.
- Work done is a direct measure of energy transfer, defined as W = Fd, where W is work (Joules), F is force (Newtons), and d is distance (meters) in the direction of the force.
- Objects possess Kinetic Energy (motion), Gravitational Potential Energy (position), and Elastic Energy (deformation).
- Hooke's Law: F = kx, where F is force (N), k is the spring constant (N/m), and x is extension (m).
- Vehicle efficiency is improved by reducing air resistance (aerodynamic losses), rolling resistance, idling losses, and inertial losses.
- Safety features like crumple zones and airbags extend the time of impact to reduce the force exerted on occupants.
What to do in an assessment
- Calculate work done: A box is pushed with 50N of force over 2m. W = 50N * 2m = 100J.
- Calculate spring extension: A spring with k = 200N/m has a 50N load. x = 50N / 200N/m = 0.25m.
In plain language
Energy is never created or destroyed, only transferred. When you push an object, you do 'work' on it, transferring energy to that object. Systems like car safety zones and efficient engine design rely on managing these transfers and forces.
Self-check
A force of 10N moves an object 5 meters in the same direction. How much work is done?
Show the answer
Work = Force x distance = 10N x 5m = 50 Joules.
Topic group
Unit 6 · 6.3 · Physics of Energy and Deformation
- Higher
Scope: Higher · Unit 6 tier: Higher · Topic 6.3 (higher)
Open revision guidance
What to know
- Kinetic Energy (KE) is calculated as KE = 1/2 * m * v^2 (m is mass in kg, v is velocity in m/s).
- Change in Gravitational Potential Energy (PE) is calculated as ΔPE = m * g * Δh (m is mass, g is gravitational field strength ~9.8N/kg, Δh is height change).
- Work done in stretching a spring is the area under a Force-Extension graph; for a linear relationship, W = 1/2 * F * x.
What to do in an assessment
- Calculate Kinetic Energy: Find the KE of a 2kg mass moving at 3m/s: KE = 0.5 * 2 * 3^2 = 9J.
- Calculate PE change: Find the change in PE for a 2kg block lifted 5m: ΔPE = 2 * 9.8 * 5 = 98J.
- Calculate work done on a spring: For a spring where 10N produces 0.1m extension, W = 0.5 * 10 * 0.1 = 0.5J.
In plain language
These higher-level formulas allow us to precisely calculate the energy stored or released by moving objects and stretching materials using mathematical models like squares and areas under graphs.
Self-check
What is the kinetic energy of a 4kg object travelling at 2m/s?
Show the answer
KE = 1/2 * m * v^2 = 0.5 * 4 * (2^2) = 0.5 * 4 * 4 = 8 Joules.
Topic group
Unit 6 · 6.4 · Astronomy: From Solar Systems to Stellar Lifecycles
- Core
Scope: Core · Topic 6.4 (core)
Open revision guidance
What to know
- The solar system consists of the Sun, 4 terrestrial planets (Mercury, Venus, Earth, Mars), 4 gaseous giants (Jupiter, Saturn, Uranus, Neptune), dwarf planets, comets, asteroids, and moons.
- Planetary order increases with distance from the Sun. Terrestrial planets are rocky; gas giants are massive with thick atmospheres.
- Observable universe components include planets, systems, stars, and galaxies.
- Distance units: Kilometre (km) for local, Astronomical Unit (AU, mean Earth-Sun distance) for solar system scale, and Light-year (l-y, distance light travels in a vacuum in one year) for interstellar/galactic distances.
- Stellar life cycle: Protostar (gas/dust collapse) -> Main Sequence (stable fusion) -> Red Giant (low/medium mass) or Supergiant (high mass).
- Final stages: Low mass -> White Dwarf; High mass -> Supernova -> Neutron star or Black hole.
- Star stability: Balance of inward gravitational pull and outward gas/radiation pressure from fusion.
- Energy generation: Fusion of hydrogen into helium and subsequently heavier elements.
- Recycling: Giant stars eject heavy elements into space during death; these, with gas and dust, collapse to form new solar systems (nebular hypothesis).
What to do in an assessment
- Contrast terrestrial planets (small, rocky, high density) vs. gas giants (massive, H/He rich, low density).
- Calculate distances between objects using unit conversions: 1 AU ≈ 1.5 x 10^8 km; 1 l-y ≈ 9.46 x 10^12 km.
- Model the star cycle stages: Protostar → Main Sequence → Red Giant/Supergiant → Remnants.
- Explain the gravitational-pressure equilibrium: If fusion stops, gravity wins; if energy increases, pressure pushes outward.
- Discuss elemental nucleosynthesis: Fusion builds elements up to Iron in stars, and heavier elements during supernova explosions.
In plain language
The solar system formed from a cloud of gas and dust enriched by the debris of previous, exploded stars. Stars are like self-regulating furnaces; they stay stable as long as they fuse atoms to push outward against their own crushing weight of gravity. When they run out of fuel, they die in spectacular ways, returning heavy atoms into space to build new worlds.
Self-check
Why does a main sequence star remain stable?
Show the answer
A main sequence star remains stable due to the equilibrium between the inward force of gravity and the outward pressure generated by gas and radiation from nuclear fusion.
Topic group
Unit 6 · 6.4 · Hertzsprung-Russell (H-R) Diagrams
- Higher
Scope: Higher · Unit 6 tier: Higher · Topic 6.4 (higher)
Open revision guidance
What to know
- The H-R diagram plots stellar luminosity (total power output) against surface temperature (or spectral class).
- The Main Sequence appears as a prominent diagonal band where most stars reside.
- Top-right contains cool, large, luminous stars (Red Giants/Supergiants).
- Bottom-left contains hot, small, dim stars (White Dwarfs).
- The diagram charts a star's evolutionary path as its properties change over time.
What to do in an assessment
- Draw an H-R diagram axes (Luminosity on Y-axis, Temperature/Spectral Type on X-axis).
- Label the regions for Main Sequence, Red Giants, and White Dwarfs.
- Trace the path of a star leaving the main sequence as it expands into a red giant.
In plain language
The H-R diagram is the 'map' astronomers use to see what stage of life a star is in. By looking at how bright a star is versus how hot it glows, we can categorise it and predict if it is a young stable star, a dying red giant, or a cooling white dwarf remnant.
Self-check
Where are white dwarfs located on an H-R diagram?
Show the answer
They are located in the bottom-left corner because they have high surface temperatures but very low luminosity due to their small size.
Topic group
Unit 6 · 6.5 · Atomic Nuclei and Radioactivity
- Core
Scope: Core · Topic 6.5 (core)
Open revision guidance
What to know
- The nucleus contains protons (proton number Z) and neutrons.
- Nucleon number A is the total number of protons and neutrons. Isotopes are atoms of the same element with different numbers of neutrons.
- Radioactive decay is caused by unstable nuclei due to an imbalance of protons and neutrons.
- Alpha particles are helium nuclei (4,2 He); Beta particles are high-energy electrons (0,-1 e); Gamma rays are high-energy electromagnetic waves.
- Alpha is blocked by paper, Beta by thin aluminium, and Gamma requires lead or thick concrete.
- Background radiation comes from natural sources (radon gas, cosmic rays, rocks) and artificial sources (X-rays, nuclear medicine).
- Radioactive decay is a random process, necessitating repeated measurements to determine accurate activity rates.
- Nuclear waste must be stored securely for long periods due to its prolonged radioactivity.
What to do in an assessment
- Calculate proton and neutron counts from A and Z values.
- Identify isotopes from atomic symbol notation.
- Subtract background radiation levels from gross experimental counts to find the true source activity.
- Evaluate safety risks by comparing penetrating powers of alpha, beta, and gamma radiation.
- Analyse data regarding radiation doses and variations in radon gas accumulation based on local geology.
In plain language
Atoms have a nucleus made of protons and neutrons. Some atoms are unstable and spit out radiation to become stable. This radiation can be dangerous depending on what it is—alpha, beta, or gamma—so we must handle radioactive waste with great care and store it for thousands of years. Because radiation happens randomly, scientists take many readings to make sure their results are accurate, while always accounting for the background radiation that is naturally all around us.
Self-check
If a detector measures 50 counts per minute near a source and the background radiation is 10 counts per minute, what is the actual activity of the source?
Show the answer
40 counts per minute (50 total minus 10 background).
Topic group
Unit 6 · 6.5 · Nuclear Decay Equations
- Higher
Scope: Higher · Unit 6 tier: Higher · Topic 6.5 (higher)
Open revision guidance
What to know
- Alpha decay symbol: 4/2 He or 4/2 α.
- Beta decay symbol: 0/-1 e or 0/-1 β.
- In nuclear equations, the total nucleon number A and total proton number Z must be equal on both sides of the equation.
What to do in an assessment
- Balance nuclear equations for alpha decay: Parent -> Daughter + Alpha particle.
- Balance nuclear equations for beta decay: Parent -> Daughter + Beta particle.
- Ensure the sum of top numbers and bottom numbers are identical on both sides of the arrow.
In plain language
To track nuclear changes mathematically, we write equations where the total number of particles is conserved. For alpha decay, the nucleus loses 2 protons and 2 neutrons (an alpha particle). For beta decay, a neutron turns into a proton and an electron (the beta particle) which is ejected.
Self-check
Balance the alpha decay of Uranium-238 (238/92 U).
Show the answer
238/92 U -> 234/90 Th + 4/2 He.
Topic group
Unit 6 · 6.6 · Radioactive Decay, Half-life, and Applications
- Core
Scope: Core · Topic 6.6 (core)
Open revision guidance
What to know
- Radioactive decay is a random process where it is impossible to predict exactly which nucleus will decay next.
- The half-life of a radioactive isotope is the time taken for the number of radioactive nuclei in a sample to decrease by half.
- Radioactive decay follows an exponential decay curve when plotting activity or count rate against time.
- Common uses of isotopes depend on their half-life, type of radiation emitted, and penetrating power.
What to do in an assessment
- Use dice or coins as a model for random decay: Each die represents a nucleus, and rolling a '6' represents a decay event. Remove 'decayed' dice and repeat.
- Plot decay curves: Place time on the x-axis and activity (in Becquerels, Bq) or count rate (in counts per second) on the y-axis.
- Calculate half-life from a graph: Find the time taken for the activity to drop from its initial value (A0) to half its value (A0/2).
- Perform half-life calculations: If a sample has an initial activity of 800 Bq and a half-life of 2 hours, after 2 hours it is 400 Bq, after 4 hours 200 Bq, and after 6 hours 100 Bq.
- Identify isotope applications: Tracers (require medium half-life and gamma emissions to penetrate the body) and cancer treatment (often use gamma or beta radiation for targeted cell destruction).
In plain language
Radioactive decay is like rolling dice: you cannot predict when any specific atom will 'decay', but you can predict how a large group will behave over time. We describe this timing using 'half-life'. By knowing the half-life and the radiation type, we can pick the right isotopes to track blood flow in the body or to kill cancer cells, balancing how long they stay dangerous with how well they can pass through tissues to be detected.
Self-check
A radioactive source has an activity of 1600 Bq. If its half-life is 3 days, what will its activity be after 9 days?
Show the answer
After 3 days: 800 Bq. After 6 days: 400 Bq. After 9 days: 200 Bq.
Topic group
Skills across the sciences
- Core
Scope: Core · shared-enquiry; core
Open revision guidance
What to know
- Develop hypotheses and devise procedures [L125]
- Select appropriate apparatus and techniques [L125]
- Use SI units, prefixes, and powers of ten [L136]
- Understand random and systematic errors [L136]
- Data quality: accuracy, precision, repeatability, and reproducibility [L136]
- Risk evaluation and ethical considerations [L125]
What to do in an assessment
- Plan investigations to ensure samples are representative [L125]
- Collect/record data accurately including uncertainty estimation [L125, L136]
- Present data via tables, graphs, and symbolic forms [L136]
- Translate data between forms and identify patterns/trends [L136]
- Evaluate methods to suggest improvements [L125]
In plain language
Scientific enquiry involves planning experiments, selecting equipment, and collecting data with awareness of errors. You must ensure results are repeatable and reproducible, use proper SI units, and evaluate your findings to draw conclusions based on evidence.
Self-check
What is the difference between repeatability and reproducibility?
Show the answer
Repeatability is achieving the same results using the same methods/equipment by the same investigator, while reproducibility involves different conditions or investigators reaching similar findings.
- Core
Scope: Core · shared-maths; core
Open revision guidance
What to know
- Arithmetic: decimal form, standard form, ratios, fractions, percentages [L158]
- Handling data: significant figures, arithmetic means, tables/diagrams [L158]
- Probability: understanding simple probability [L158]
- Algebra: substitute numerical values and solve equations, change the subject [L158]
- Graphs: y=mx+c linear relationship, plotting variables, interpret slope and intercept [L158]
- Geometry: angular measures, area of triangles/rectangles, surface area/volume [L158]
What to do in an assessment
- Convert between units (e.g., km to m, g to kg) [L136]
- Perform order of magnitude calculations [L158]
- Calculate area of a rectangle (base x height) or volume of a cube (side³) [L158]
- Determine the gradient (m) and y-intercept (c) from a linear graph [L158]
- Solve for variables in physical formulae [L158]
In plain language
Mathematical skills are essential for science. You must be able to handle arithmetic, work with significant figures and units, use algebra to manipulate formulae, and construct/interpret linear graphs and geometric shapes.
Self-check
If y = 3x + 2, what is the gradient and the y-intercept?
Show the answer
The gradient (m) is 3 and the y-intercept (c) is 2.
- Higher
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
- Tangents: Using the gradient of a tangent to determine instantaneous rate of change [L158]
- Area under curves: Physical significance of area between a curve and the x-axis [L158]
What to do in an assessment
- Draw a tangent to a curve at a point and calculate gradient (dy/dx ≈ rise/run) [L158]
- Estimate area under a curve by counting squares [L158]
In plain language
Higher tier maths requires interpreting curved graphs. You must find the rate of change by drawing a tangent and calculating its gradient, and estimate physical quantities (like displacement) by counting squares under a curve.
Self-check
How do you find the instantaneous rate of change from a curved graph?
Show the answer
Draw a tangent to the curve at the specific point and calculate the gradient (slope) of that straight line.
Topic group
Unit 7 Practical Assessment Guidance
- Core
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
- Assessment structure: Two tasks chosen by the centre (Biology/Chemistry/Physics) [L114]
- Section A: Obtaining results, 60 minutes, group work allowed (max 3), 6 marks [L114]
- Section B: Analysis and evaluation, 60 minutes, individual work, 24 marks [L114]
What to do in an assessment
- Perform experiments to obtain results in Section A [L114]
- Analyze/evaluate data and answer questions individually in Section B [L114]
- Ensure all data presented follows scientific notation and significant figure rules [L136]
In plain language
Unit 7 is an externally marked practical assessment worth 10% of your grade. You collect data in groups for Section A, then analyse that data individually under formal exam conditions in Section B.
Self-check
Are you allowed to receive teacher help during Section B?
Show the answer
No, Section B is conducted under high control with no teacher feedback or assistance allowed.
Topic group
Unit 3 · practical:3.1 · Investigation of Current-Voltage (I-V) Characteristics
- Core
Scope: Core · Topic practical:3.1 (core)
Open revision guidance
What to know
- Ohm's Law: V=IR
- Linear components (resistors) show a constant resistance
- Non-linear components (filaments, diodes) have resistance that changes with voltage/current
What to do in an assessment
- Set up a circuit with a DC power supply, variable resistor (or variable voltage source), component, ammeter in series, and voltmeter in parallel across the component.
- Adjust the power supply to record current at different voltage increments.
- Reverse the power supply connections to record values for negative voltage/current.
- Plot a graph of current (y-axis) against voltage (x-axis).
- Calculate resistance (R=V/I) from the gradient for linear components.
In plain language
This experiment tests how different electrical components respond when the voltage across them is changed. By measuring the current flowing through a component as you alter the voltage, you can identify if it follows Ohm's Law or if its resistance changes under different conditions.
Self-check
If a resistor has a voltage of 4V and a current of 0.5A, what is its resistance?
Show the answer
Using R=V/I, R=4/0.5 = 8 Ohms.
Topic group
Unit 3 · practical:3.3 · Heat Transfer Methods and Density Determination
- Core
Scope: Core · Topic practical:3.3 (core)
Open revision guidance
What to know
- Conduction, convection, and radiation are the three methods of heat transfer.
- Density is mass divided by volume (ρ = m/V).
- Regular solids have geometric dimensions for volume calculation; irregular solids require displacement methods.
What to do in an assessment
- For heat transfer: Observe conduction via metal rod with wax, convection in potassium permanganate water, and radiation using a Leslie cube with an infrared detector.
- For density: Measure mass using a digital balance. For regular solids, use a ruler for dimensions. For irregular objects and liquids, use a displacement can or measuring cylinder to find volume by water displacement.
- Ensure all electrical apparatus for heating is used under teacher supervision.
- Calculate density by dividing the mass (g) by the measured volume (cm³).
In plain language
This lesson covers how heat moves and how to calculate the density of different objects. You will observe heat moving through solids, liquids, and space, and use scales and water displacement to measure mass and volume to find density.
Self-check
If an irregular stone has a mass of 50g and displaces 20cm³ of water, what is its density?
Show the answer
Using the formula density = mass / volume, 50g / 20cm³ = 2.5g/cm³.
Topic group
Unit 3 · practical:3.5 · Investigation of the speed of water waves
- Core
Scope: Core · Topic practical:3.5 (core)
Open revision guidance
What to know
- Wave speed is calculated by frequency multiplied by wavelength.
- Measurements must be taken consistently to minimise error.
- A ripple tank is the standard apparatus to generate and observe waves.
What to do in an assessment
- Set up a ripple tank with a shallow depth of water and a dipper.
- Adjust the dipper frequency until stable waves are observed.
- Use a strobe light or stopwatch to measure the frequency (f).
- Use a meter ruler to measure the length of 10 waves and divide by 10 to find the wavelength (λ).
- Calculate wave speed (v) using v = f × λ.
- Supervise pupils near electrical equipment; ensure water is kept away from power sources.
In plain language
You will measure how fast waves travel across a tank of water by finding out how many waves pass per second and how long each wave is.
Self-check
If 10 waves measure 0.5 meters and the frequency is 2 Hz, what is the wave speed?
Show the answer
Wavelength = 0.5m / 10 = 0.05m. Speed = 2 Hz × 0.05m = 0.1 m/s.
Topic group
Unit 6 · practical:6.2 · Investigation of the terminal speed of a falling object
- Core
Scope: Core · Topic practical:6.2 (core)
Open revision guidance
What to know
- Terminal speed occurs when the weight of a falling object is equal to the drag force acting on it, resulting in zero resultant force and constant velocity.
- The object will accelerate initially before reaching this constant terminal speed.
What to do in an assessment
- Apparatus: A tall measuring cylinder filled with viscous liquid (e.g., washing-up liquid), small spherical objects (e.g., steel ball bearings), a stopwatch, a meter ruler, and elastic bands.
- Method: Place elastic bands at fixed intervals (e.g., every 5 cm) along the measuring cylinder starting from below the expected acceleration zone. Drop the sphere and use the stopwatch to record the time taken to travel between each pair of elastic bands.
- Measurements: Distance between elastic bands and time taken for the sphere to travel each interval.
- Control strategy: Ensure the sphere is released from the same point each time; the same liquid and container must be used throughout.
- Safety: Wipe up any liquid spills immediately to prevent slipping; ensure the cylinder is secure on a level surface.
- Calculations: Calculate speed for each interval (v = distance/time). Worked example: If the sphere travels 0.05m in 0.4 seconds, speed = 0.05 / 0.4 = 0.125 m/s.
- Analysis: If the speed remains constant between intervals, terminal speed has been reached.
- Limitations: Reaction time causes measurement uncertainty; parallax error when reading the stopwatch/ruler. Improvements: Use light gates to eliminate human reaction time.
In plain language
This experiment finds the constant maximum speed a ball reaches as it falls through a thick liquid. By marking points and timing how long the ball takes to pass between them, you can see if the ball has stopped speeding up.
Self-check
How do you know when terminal speed has been reached?
Show the answer
Terminal speed is reached when the time taken to travel between equal-distance intervals remains constant, meaning the speed is no longer increasing.
Topic group
Unit 6 · practical:6.3 · Investigation of the Force-Extension Graph for a Spring
- Core
Scope: Core · Topic practical:6.3 (core)
Open revision guidance
What to know
- Hooke's Law states that force is directly proportional to extension for a spring, provided it is not stretched beyond its limit of proportionality.
- The relationship is expressed as F=ke, where F is force, k is the spring constant, and e is extension.
- The graph of force (y-axis) against extension (x-axis) is a straight line through the origin when the spring obeys Hooke's Law.
- Safety: Wear safety goggles to protect against flying fragments if the spring breaks, and use a G-clamp to secure the retort stand to the bench to prevent tipping.
What to do in an assessment
- Set up a retort stand with a G-clamp, a spring, a meter ruler, and a pointer.
- Measure the initial length of the unstreched spring.
- Add a 1N weight and record the new length; subtract the initial length to find the extension.
- Repeat by adding 1N increments up to approximately 5-7N, measuring the total length each time.
- Plot force (N) on the vertical axis and extension (m) on the horizontal axis.
- Calculate the spring constant (k) by finding the gradient of the straight-line portion (gradient = change in force / change in extension).
In plain language
This experiment tests how much a spring stretches when different weights are added. You measure the stretch each time you add a weight to see if the spring follows Hooke's Law, which says stretching is proportional to the force applied. Note: Reading these instructions does not replace completing the assessed practical performance under school supervision.
Self-check
If a spring stretches 0.05m when a 2N weight is added, what is the spring constant k?
Show the answer
Using F=ke, k = F/e. So, k = 2N / 0.05m = 40 N/m.
Topic group
Unit 6 · practical:6.6 · Determining Half-Life Using a Dice Model
- Core
Scope: Core · Topic practical:6.6 (core)
Open revision guidance
What to know
- Radioactive decay is a random process where a nucleus decays unpredictably.
- Half-life is the time it takes for half of the radioactive nuclei in a sample to decay.
- A large number of dice acts as a model for radioactive atoms, where rolling a 6 represents a decay event.
What to do in an assessment
- Obtain 100 dice and a tray.
- Place all 100 dice in the tray. This is 'Time 0'.
- Shake the tray and roll the dice. Remove all dice showing a 6. These are 'decayed'.
- Record the number of remaining dice.
- Repeat the process with the remaining dice for 10-15 'rolls' or until very few dice remain.
- Use a scatter graph with 'Number of Rolls' on the x-axis and 'Remaining Dice' on the y-axis to plot the results.
- Identify the half-life by finding the number of rolls required for the number of dice to fall from 100 to 50, and then from 50 to 25.
In plain language
This experiment uses dice to represent radioactive atoms. Each time you roll, the dice that land on 6 are removed, just like radioactive atoms that decay and become stable. By counting how many are left after each roll, you can calculate the 'half-life' (how long it takes for half the pile to disappear).
Self-check
If you start with 100 dice and have 50 left after 3 rolls, what is the half-life?
Show the answer
The half-life is 3 rolls, because it took 3 rolls for the initial population of 100 to reduce by half to 50.
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