Define current sensitivity and voltage sensitivity of a galvanometer.
Increasing the current sensitivity may not necessarily increase the voltage sensitivity of a galvanometer. Justify.

Explanation

The current sensitivity of a galvanometer is defined as the deflection per unit current.
`:.` Current sensitivity `phi/I = (NAB)/(k)`, where`k`= restoring torque per unit deflection.
The voltage sensitivity of a galvanometer is defined as the deflection per unit voltage.
`:.` Voltage sensitivity `phi/V = (NAB)/k cdot 1/R`, where R is the resistance of the galvanometer.
Increase in current sensitivity may not necessarily increase the voltage sensitivity. To explain it let us double the number of turns N of galvanometer coil. So as to double the current sensitivity. However, on doubling the number of turns the resistance of galvanometer coil is also doubled from R to 2R consequently voltage sensitivity remains unchanged.