The resistance of the galvanometer $G$ in the circuit is $25\Omega$. The meter deflects full scale for a current of $10 \mathrm{mA}$. The meter behaves as an ammeter of three different ranges. The range is $0-10 \mathrm{A}$, if the terminals $O$ and $P$ are taken; range is $0-1 \mathrm{A}$ between $O$ and $Q$; range is $0-0.1 \mathrm{A}$ between $O$ and $R$. Calculate the resistance $R_1$, $R_2$ and $R_3$.

 

A galvanometer (coil resistance $99\Omega$ ) is converted into a ammeter using a shunt of $1\Omega$ and connected as shown in the figure (i). The ammeter reads $3A$. The same galvanometer is converted into a voltmeter by connected a resistance of $101\Omega$  in series. This voltmeter is connected as shown in figure (ii). Its reading is found to be $\frac{4}{5}$ of the full scale reading. Find

(i) internal resistance $r$ of the cell