Question

Increasing the current sensitivity of a galvanometer may not necessarily increase its voltage sensitivity. Explain, giving reason.

Answer 1

The current sensitivity of a moving coil galvanometer is given by `(nBA)/k`, where n is the number of turns , A is the area of the coil , B is the magnetic field strength of the poles and k is the spring's constant of the suspension wire.

Similarly, voltage sensitivity is given by `(nBA)/(kR)`, where R is the resistance of the wire.

From the above two expressions, we get:

Voltage sensitivity = Current sensitivity/R

Thus, on increasing the current sensitivity, voltage sensitivity may or may not increase because of similar changes in the resistance of the coil, which may also increase due to increase in temperature.