Question

A compass needle is placed near a current carrying wire. State your observation for the following cases, and give reason for the same in each case. a) Magnitude of electric current in the wire is increased. b) The compass needle is displaced away from the wire.

Answer 1

a)If the magnitude of current is increased ,then the deflection of the compass will increase as the electric field created by the wire in turn creates a magnetic field which deflects the compass needle.

b)if it is displaced from the wire then the deflection will decrease as the magnetic field becomes weaker with increase in distance.

Answer 2

When a compass needle is placed in a current-carrying wire, observation and reasons are as follows:

a) Magnitude of the electric current increases.

• When the needle is placed in the current-carrying field, it experiences more current.
• As the current magnitude is increased, the compass needle deflection also increases.
• This means the magnetic field strength the compass needle experiences increase.
• This is because current and magnetic field strength are proportional directly.

b) The compass needle gets displaced from the wire.

• When the compass needle is moved away from the wire, the deflection of the needle will decrease.
• This is because the magnetic field strength the needle experiences decreases.