Question

To increase the current sensitivity of a moving coil galvanometer by 50%, its resistance is increased so that the new resistance becomes twice its initial resistance. By what factor does the voltage sensitivity change?

Answer 1

Let current Sensitivity and voltage Sensitivity be the original current sensitivity and voltage sensitivity of the moving coil galvanometer respectively.

Now current sensitivity I is given by

I' = I + 50/160 I

I' = 3/2 I

V' = I'/R

V' = 3/2I / 2R

V' = 0.75 vs

thus the voltage sensitivity decrease by 25%.