The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50 \%$. The percentage change in voltage sensitivity of the galvanometer will be $..........\%$

Two moving coil meters,$M_{1}$ and $M_{2}$ have the following particulars:
$R_{1}=10 \,\Omega, \quad N_{1}=30$
$A_{1}=3.6 \times 10^{-3} \,m^{2}, \quad B_{1}=0.25 \,T$
$R_{2}=14 \,\Omega, \quad N_{2}=42$
$A_{2}=1.8 \times 10^{-3} \,m^{2}, \quad B_{2}=0.50 \,T$
(The spring constants are identical for the two meters). Determine the ratio of
$(a)$ current sensitivity and
$(b)$ voltage sensitivity of $M_{2}$ and $M_{1}$.

$A$ shunt of resistance $1\,\Omega$ is connected across a galvanometer of $120\,\Omega$ resistance. $A$ total current of $5.5\,A$ is passed through the combination,which gives full-scale deflection in the galvanometer. The current that would give full-scale deflection in the absence of the shunt is nearly ............... $A$.

Explain the construction and principle of a moving coil galvanometer.

Which of the following statements is correct?

The resistance of an ideal voltmeter is . . . . . . .