Question

In the circuit shown in Fig., when the key is closed, the compass needle placed in the matchbox deflects. Name the force which causes this deflection.

(2)

Answer 1

Magnetic effects of electric current

1. All magnetic effects are associated with electric current.
2. Moving charge generates a current which in turn generates a magnetic field.
3. The magnetic field produced by a bar magnet can be explained as a resultant field produced by the tiny current loops formed by the electrons revolving around the nucleus of each atom.

Analyze the deflection

1. In the given figure when the key is closed current passes through the circuit.
2. As we know a flowing current produces a magnetic field.
3. A compass needle gets deflected when it detects the presence of a magnetic field.
4. Hence, the force which causes this deflection is the magnetic force.