Write the equation for the series resistance required to increase the voltage range of a galvanometer by a factor of $n$.

$A$ galvanometer with its coil resistance $25\,\Omega$ requires a current of $1\,mA$ for its full-scale deflection. In order to construct an ammeter to read up to a current of $2\,A$,the approximate value of the shunt resistance should be:

$A$ galvanometer of resistance $240 \Omega$ allows only $4 \%$ of the main current to pass through it after connecting a shunt resistance. The value of the shunt resistance is (in $Omega$)

In the circuit diagrams ($A, B, C$ and $D$) shown below,$R$ is a high resistance and $S$ is a resistance of the order of galvanometer resistance $G$. The correct circuit,corresponding to the half deflection method for finding the resistance and figure of merit of the galvanometer,is the circuit labelled as

Two moving coil meters $M_1$ and $M_2$ have the following particulars:
$R_1 = 10\,\Omega, N_1 = 30, A_1 = 3.6 \times 10^{-3}\, m^2, B_1 = 0.25\, T$
$R_2 = 14\,\Omega, N_2 = 42, A_2 = 1.8 \times 10^{-3}\, m^2, B_2 = 0.50\, T$
(The spring constants are identical for the two meters). Determine the ratio of voltage sensitivity of $M_2$ and $M_1$.

In an ammeter,$0.25 \%$ of the main current passes through the galvanometer. If the resistance of the galvanometer is $G$,the resistance of the ammeter will be: