Key term
AQA GCSE Combined Science Physics 8464
Atomic Structure
Topic overviewThe structure of an atomMass number, atomic number and isotopesFrom the plum pudding model to the nuclear modelChadwick, the neutron, and comparing the modelsRadioactive decay and nuclear radiationNuclear equationsHalf-lives and the random nature of radioactive decayRadioactive contamination
Electricity
Topic overviewCircuit symbols, electrical charge and currentCurrent, resistance and potential differenceOhmic conductors, filament lamps, diodes and thermistorsLight-dependent resistors, and investigating resistanceCurrent and potential difference in series and parallelConstructing circuits, and calculating in series circuitsDirect and alternating potential difference, and mains electricityPower and efficiencyAppliances, and the energy transferred by electrical workPower, and the power ratings of domestic appliancesThe National Grid
Energy
Forces
Topic overviewScalars, vectors, forces and the resultant forceGravityWork done and energy transferStretching, compressing, and the spring constantLinear and non-linear extension, and work done on a springResolving forces and free body diagramsDistance, displacement and speedThe speed of sound, and the distance-speed-time equationVelocity and the distance-time relationshipAcceleration, deceleration and velocity-time graphsArea under a velocity-time graph, and the uniform acceleration equationNewton's First LawNewton's Second and Third LawsStopping distance and reaction timeFactors affecting braking distanceBraking force, deceleration and the dangers of stopping quicklyMomentum and its conservation
Magnetism and Electromagnetism
Particle Model of Matter
Energy
Power
- 3 things to know
- Physics Paper 1
Overview
What power is and how it differs from energy transferred, power in terms of energy transferred and time and of work done and time with calculations, converting kilojoules and minutes into joules and seconds, one watt as one joule per second, and comparing motors and kettles of different power.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain the difference between the energy transferred by a device and its power.
Key term
State the equation for power in terms of energy transferred and time.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define power.
Model answer
Power is the rate at which energy is transferred, or the rate at which work is done.
- 2
Explain the difference between the energy transferred by a device and its power.
Model answer
The energy transferred is the total amount moved between stores, while the power is the amount transferred each second.
- 3
State the equation for power in terms of energy transferred and time.
Model answer
Power = energy transferred ÷ time, or P = E ÷ t.
- 4
A heater transfers 6000 J of energy in 30 s. Calculate its power.
Model answer
P = 6000 ÷ 30 = 200 W.
- 5
A lamp of power 60 W is switched on for 120 s. Calculate the energy it transfers.
Model answer
E = 60 × 120 = 7200 J.
- 6
Calculate the time a 300 W motor takes to transfer 9000 J of energy.
Model answer
t = 9000 ÷ 300 = 30 s.
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