Sensitivity of a Galvanometer:
A galvanometer is said to be sensitive if a small current flowing through the coil of galvanometer produces a large deflection in the galvanometer.
(i) Current Sensitivity:
The current sensitivity of a Galvanometer is defined as the deflection produced in the coil of the galvanometer per unit current flowing through it.
$$Current \ sensitivity = \frac{\phi}{I}$$
$$Current \ sensitivity = \frac{\phi}{\frac {k\phi}{NAB}}$$
$$Current \ sensitivity = \frac{\phi NAB}{k\phi}$$
$$Current \ sensitivity = \frac{NAB}{k}$$
Current sensitivity can be increased by :
(a) Increasing N
(b) Increasing B
(C) Increasing A
(d) Decreasing k
(ii) Voltage sensitivity:
Voltage sensitivity of a Galvanometer is defined as the deflection produced in the coil of the galvanometer per unit voltage applied to it.
$$Voltage sensitivity= \frac{\phi}{V}$$
$$Voltage sensitivity= \frac{\phi}{IR}$$
$$Voltage\ sensitivity = \frac{\phi} {\frac{k\phi R}{(NAB)}}$$
$$Voltage\ sensitivity = \frac{\phi (NAB)}{k\phi R}$$
$$Voltage \ sensitivity = \frac{NAB}{kR}$$
Voltage sensitivity can be increased by :
(a) Increasing N
(b) Increasing B
(C) Increasing A
(d) Decreasing k
(e) Decreasing R