How a changing magnetic field induces an e.m.f., the factors that affect its size, predicting the direction with Fleming’s right-hand rule, and how an a.c. generator produces alternating current.
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.
Moving a magnet in and out of a coil makes a current appear with no battery at all. That discovery lit the world.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Turn the coil and watch the induced voltage.
Copy these into your notebook in your own words — that is how they stick.
Produced when a conductor cuts magnetic field lines (relative motion).
No induced e.m.f.
Speed, magnet strength, number of turns.
Fleming’s right-hand rule; Lenz’s law (opposes the change).
Coil rotating in a field; slip rings and brushes.
Sine wave; frequency = rotations per second.
When the coil cuts field lines fastest (horizontal).
Motor: current → motion; generator: motion → current.
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 student connects a coil to a sensitive centre-zero galvanometer and moves a bar magnet.
(a) (a) Describe what is observed when the magnet is pushed quickly into the coil and then held still. [3]
(b) (b) State two ways of making the induced e.m.f. larger. [2]
(c) (c) State what happens when the magnet is pulled out. [1]
(d) (d) Name the rule used to predict the direction of the induced current in a conductor moving in a field. [1]
(e) (e) Describe how an a.c. generator produces an alternating e.m.f. [4]
(f) (f) The generator turns at 50 rotations per second. State the frequency of the output and the period. [3]
(g) (g) State one difference between a motor and a generator. [1]
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.