| English | Force on a current-carrying conductor |
|---|---|
| Bahasa Melayu | Daya pada konduktor pembawa arus |
| 中文 | 载流导体所受的力 |
Definition
The force experienced by a current-carrying conductor placed in a magnetic field, at right angles to both the current and the field.
In exam terms
The force on a current-carrying conductor is the force felt by a wire carrying current when it is placed in a magnetic field, acting at right angles to both the current and the field. This is the catapult effect that drives electric motors.
The force is measured in newtons (N).
The force is larger when the current is larger, the magnetic field is stronger, or the length of wire in the field is greater, and it is greatest when the wire is perpendicular to the field. Its direction is found using Fleming's left-hand rule: thumb for thrust (force), first finger for field, second finger for current.
Example of correct use: Reversing the current reverses the direction of the force on the conductor.
Do not confuse it with…
Do not confuse this with electromagnetic induction. Here a current is supplied to a conductor in a field and a force results (motor effect); in induction, movement or a changing field produces an e.m.f. and current (generator effect).
Also use Fleming's left-hand rule here, not the right-hand rule which is for induction.
In Paper 2 this is asked as state or explain: state the direction of the force using Fleming's left-hand rule, or explain how to increase the force. When answering, always name the rule and match thumb, first and second fingers to force, field and current.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)