In a ballistic galvanometer,the frame on which the coil is wound is non-metallic to

$A$ multirange voltmeter can be constructed by using a galvanometer circuit as shown in the figure. We want to construct a voltmeter that can measure $2 \ V$,$20 \ V$,and $200 \ V$ using a galvanometer of resistance $10 \ \Omega$ that produces maximum deflection for a current of $1 \ mA$. Find $R_1$,$R_2$,and $R_3$ that have to be used.

Explain the solution to the difficulties that arise when using a galvanometer directly as an ammeter.

The sensitivity of a galvanometer that measures current is decreased by $\frac{1}{40}$ times by using a shunt resistance of $10 \Omega$. Then,the value of the resistance of the galvanometer is (in $\Omega$)

In a galvanometer,the deflection becomes one half when the galvanometer is shunted by a $20\,\Omega$ resistor. The galvanometer resistance is ............... $\Omega$.

Give the unit of shunt.