What is voltage sensitivity? Obtain its equation.

(N/A) Voltage sensitivity is defined as the deflection produced in a galvanometer per unit voltage applied across it.
Let the deflection be $\phi$ for a current $I$. The deflection in a moving coil galvanometer is given by $\phi = \left(\frac{NAB}{k}\right) I$,where $N$ is the number of turns,$A$ is the area,$B$ is the magnetic field,and $k$ is the restoring torque per unit twist.
Dividing both sides by voltage $V$,we get:
$\frac{\phi}{V} = \left(\frac{NAB}{k}\right) \frac{I}{V}$
Since $V = IR$,we have $\frac{I}{V} = \frac{1}{R}$.
Substituting this into the equation,we get the expression for voltage sensitivity $(V_s)$:
$V_s = \frac{\phi}{V} = \frac{NAB}{kR}$