Energy conversions in electrical devices, potential difference V = E/Q, power P = IV and energy E = Pt, the kilowatt-hour, and the importance of conserving electrical energy.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
A phone charger, a kettle and a lamp all draw from the same socket, but they use energy at very different rates. Power tells you which one will cost the most.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Lamp: electrical → light + thermal; motor: electrical → kinetic; battery: chemical ↔ electrical.
V = E/Q; volt = J/C.
Energy given by a cell to each coulomb of charge.
P = IV; P = E/t; watt.
E = Pt = IVt; joule.
kWh = kW × h; 1 kWh = 3.6 × 10⁶ J.
kWh × price per kWh.
LED lamps, solar heaters, efficient appliances, switch off.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (15 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [15 marks]
A small motor operates on a 12 V supply and draws 2.0 A for 15 s to lift a load.
(a) (a) Name the main energy change in the motor. [2]
(b) (b) Calculate the power supplied to the motor. [3]
(c) (c) Calculate the electrical energy transferred in 15 s. [3]
(d) (d) The motor lifts a load of 20 N through 12 m in 15 s. Calculate the useful work done and the efficiency of the motor. [4]
(e) (e) State the p.d. across a component when 10 J is transferred to each coulomb of charge passing through it. [1]
(f) (f) A 2.0 kW kettle is used for 6 minutes each day. Calculate the energy used in kWh in one day. [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.