Galvanometer Questions

A galvanometer of resistance $50\Omega$ is connected to a battery of $3\text{V}$ along with a resistance of $2950\Omega$ in series. A full scale deflection of $30$ divisions is obtained in the galvanometer. In order to reduce this deflection to $20$ divisions, the resistance in series should be:

A galvanometer having a coil resistance of $60\Omega$ shows full scale deflection when a current of $1.0\text{A}$ passes through it. It can be converted into an ammeter to read currents up to $5.0\text{A}$ by:

A galvanometer of resistance $G$ is shunted by a resistance $S$ ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is:

In the circuit shown the cells $A$ and $B$ have negligible resistances. For $V_A=12\text{V},R_1=500\Omega$ and $R=100\Omega$ the galvanometer ($G$) shows no deflection. The value of $V_B$ is: