(N/A) Voltage sensitivity of a galvanometer is defined as the deflection produced per unit voltage applied across it.
It is denoted by $V_s$.
If a voltage $V$ is applied across a galvanometer and it produces a deflection $\theta$,then voltage sensitivity is given by:
$V_s = \frac{\theta}{V}$
Since $V = I R_g$,where $I$ is the current and $R_g$ is the resistance of the galvanometer,we can write:
$V_s = \frac{\theta}{I R_g}$
Since current sensitivity $I_s = \frac{\theta}{I}$,the equation becomes:
$V_s = \frac{I_s}{R_g}$
Where $I_s = \frac{NAB}{k}$ ($N$ is the number of turns,$A$ is the area,$B$ is the magnetic field,and $k$ is the restoring torque per unit twist).