In the circuit shown in Fig.11.6, when the key is closed, the compass needle placed in the match box deflects. Name the force which causes this deflection.

The magnetic force causes the deflection because:

i. When the key is closed, the current starts flowing in the wire.

ii. Due to the flowing current, the magnetic field is produced around the circuit.

iii. This exerts a magnetic force on the needle.

iv. As a result, needle gets deflected.