$A$ galvanometer acting as a voltmeter should have . . . . . . .

$A$ galvanometer of resistance $50 \ \Omega$ giving full scale deflection for a current of $10 \ mA$ is to be changed into a voltmeter of range $100 \ V$. $A$ resistance of . . . . . . $\Omega$ has to be connected in series with the galvanometer.

To verify Ohm's law,a student is provided with a test resistor $R_T$,a high resistance $R_1$,a small resistance $R_2$,two identical galvanometers $G_1$ and $G_2$,and a variable voltage source $V$. The correct circuit to carry out the experiment 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 $M_2$?

Match the terms given in List-$I$ with suitable options provided in List-$II$ regarding the experiment to calculate the resistance and figure of merit of a galvanometer using the half-deflection method:

List-$I$	List-$II$
$A$. Figure of merit $(k)$	$P$. in series
$B$. Current sensitivity $(SI)$	$Q$. to get power loss minimized
$C$. Deflection is made half by using low resistance	$R$. in shunt/parallel
$D$. High resistance box	$S$. current per unit deflection
	$T$. deflection per unit current

In the diagram shown,the reading of the voltmeter is $20\, V$ and that of the ammeter is $4\, A$. The value of $R$ should be (Consider the given ammeter and voltmeter are not ideal).