Give the difference between an Ammeter and a Voltmeter.

The magnets of two suspended coil galvanometers are of the same strength so that they produce identical uniform magnetic fields in the region of the coils. The coil of the first one is in the shape of a square of side $a$ and that of the second one is circular of radius $\frac{a}{\sqrt{\pi}}.$ When the same current is passed through the coils, the ratio of the torque experienced by the first coil to that experienced by the second one is

$A$ galvanometer of resistance $30 \Omega$ is connected to a battery of emf $2 \text{ V}$ with $1970 \Omega$ resistance in series. $A$ full-scale deflection of $20$ divisions is obtained in the galvanometer. To reduce the deflection to $10$ divisions,the total resistance in series required is: (in $\Omega$)

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 $..........\%$

$A$ voltmeter with internal resistance of $x\text{ }\Omega$ can be used to measure up to $20\text{ V}$. In order to increase its measuring range to $30\text{ V}$, the required modification is to . . . . . . .

$A$ galvanometer of resistance $100 \Omega$ gives full scale deflection for a current of $1 \text{ mA}$. It is converted into an ammeter of range $0 - 10 \text{ A}$. The shunt required is: (in $\text{ }\Omega$)