Question

Define the current sensitivity and voltage sensitivity of a moving coil galvanometer.

Answer 1

Current sensitivity is the measure of responsiveness of any instrument to the change of current through it.
Voltage sensitivity is the measure of responsiveness of any instrument to the change of applied voltage across it.

Answer 2

Current sensitivity of a galvanometer is defined as the minimum current required to cause a deflection in the galvanometer.

That is

Si = i/∅=i/d

In case of moving coil galvanometer

i/∅=c/nAB=Si