| English | Electromagnetic induction |
|---|---|
| Bahasa Melayu | Aruhan elektromagnet |
| 中文 | 电磁感应 |
Definition
The production of an electromotive force in a conductor when there is a changing magnetic field linking it.
In exam terms
Electromagnetic induction is the production of an electromotive force (e.m.f.) in a conductor when the magnetic field linking it changes. The induced e.m.f. is measured in volts (V); if the conductor forms a closed circuit, an induced current flows.
You can induce an e.m.f. by moving a magnet in or out of a coil, moving a conductor across a magnetic field, or switching a nearby current on and off. The size of the induced e.m.f. increases with a faster rate of change of the field, more turns on the coil, and a stronger magnet.
Example of correct use: Moving the magnet into the coil faster gives a larger induced e.m.f. and a bigger galvanometer deflection.
Do not confuse it with…
Do not confuse electromagnetic induction with the motor effect (force on a current-carrying conductor). Induction is the reverse process: motion or a changing field produces an e.m.f., which is the generator effect and uses Fleming's right-hand rule.
The motor effect supplies current to get force and uses the left-hand rule.
In Paper 2 this is asked as define or explain: define electromagnetic induction, or explain how the e.m.f. can be increased. When explaining, always link the induced e.m.f. to a changing magnetic field, not merely a stationary magnet.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)