Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R). 

As the number of turns increases, length of the coil wire also increases, which increases the resistance of the coil.

Current sensitivity:

${\mathrm{S}}_{\mathrm{i}}=\left(\frac{\mathrm{\theta }}{\mathrm{I}}\right)=\frac{\mathrm{NAB}}{\mathrm{C}}$ 

Voltage sensitivity:

${\mathrm{S}}_{\mathrm{v}}=\frac{\mathrm{\theta }}{\mathrm{V}}=\frac{\mathrm{NAB}}{\mathrm{GC}}$

Where G is resistance of galvanometer.

$\Rightarrow \frac{{\mathrm{S}}_{\mathrm{v}}}{{\mathrm{S}}_{\mathrm{i}}}=\frac{1}{\mathrm{G}}\Rightarrow {\mathrm{S}}_{\mathrm{V}}=\frac{1}{\mathrm{G}}{\mathrm{S}}_{\mathrm{i}}$

Clearly the voltage sensitivity depends on current sensitivity and the resistance of galvanometer. If we increase current sensitivity, then it is not certain that voltage sensitivity will be increased because the resistance also increases. Thus, the increase of current sensitivity does not imply the increases of voltage sensitivity.