$A$ galvanometer coil has a resistance $90\, \Omega$ and full-scale deflection current $10\, mA$. $A$ $910\, \Omega$ resistance is connected in series with the galvanometer to make a voltmeter. If the least count of the voltmeter is $0.1\, V$,the number of divisions on its scale is:

In an ammeter,$5 \%$ of the main current passes through the galvanometer. If the resistance of the galvanometer is $G$,the resistance of the ammeter will be:

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:

Certain galvanometers have a fixed core made of non-magnetic metallic material. The function of this metallic material is

$A$ voltmeter having a resistance of $50 \times 10^3 \, \Omega$ is used to measure the voltage in a circuit. To increase the range of measurement $3$ times,the additional series resistance required is: