With a resistance '$X$' connected in series with a galvanometer of resistance $100 \Omega$, it acts as a voltmeter of range $0 - 15 \text{ V}$. To double the range, a resistance of $1500 \Omega$ is to be connected in series with '$X$'. The value of '$X$' in $\Omega$ is

In a moving coil galvanometer,two moving coils $M_1$ and $M_2$ have the following particulars:
$R_1 = 5 \ \Omega, N_1 = 15, A_1 = 3.6 \times 10^{-3} \ m^2, B_1 = 0.25 \ T$
$R_2 = 7 \ \Omega, N_2 = 21, A_2 = 1.8 \times 10^{-3} \ m^2, B_2 = 0.50 \ T$
Assuming that the torsional constant of the springs is the same for both coils,what will be the ratio of the voltage sensitivity of $M_1$ and $M_2$?

$A$ voltmeter of range $3 \, V$ and resistance $200 \, \Omega$ cannot be converted to an ammeter of range

$A$ moving coil galvanometer has $100$ turns and each turn has an area of $2.0 \,cm^2$. The magnetic field produced by the magnet is $0.01 \,T$ and the deflection in the coil is $0.05$ radian when a current of $10 \,mA$ is passed through it. The torsional constant of the suspension wire is $x \times 10^{-5} \,N-m / rad$. The value of $x$ is . . . . . . .

The current flowing through a coil of resistance $900 \, \Omega$ is to be reduced by $90 \, \%$. What value of shunt should be connected across the coil in $\Omega$?

The sensitivity of a moving coil galvanometer is $s$. If a shunt of $\frac{1}{8}$ of the resistance of the galvanometer is connected to the moving coil galvanometer,what will its new sensitivity be?