Question

In order to increase the sensitivity of a moving coil galvanometer:

• A. the magnetic field should be increased.
• B. the suspension wire should be made stiff.
• C. the area of the coil should be reduced.
• D. the number of turns in the coil should be reduced.

Answer 1

The correct option is A the magnetic field should be increased.

Moving coil galvanometer is based on the fact that when a current carrying coil is placed in a magnetic field , it experiences a torque.
The deflection torque is counter balanced by restoring torque using a spring system.
equating both will give,
$NIBA=k\theta$
Current sensitivity of the galvanometer is defined as deflection per unit current:
$\theta /I=NAB/k$
which means increasing the magnetic field will increase the sensitivity.