See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it?

$A$ uniform wire of length $200 \, cm$ is connected to a battery, two resistors and a galvanometer as shown in the figure. The galvanometer shows null deflection when the jockey $J$ is at $80 \, cm$ from point $A$. If the resistor $R_2$ is shunted with $30 \, \Omega$ resistance, the galvanometer shows null deflection when the jockey $J$ is at $100 \, cm$ from point $B$. Then the values of $R_1$ and $R_2$ respectively are

In the given circuit, what is the potential difference between $X$ and $Y$ in $V$?

In the circuit,the galvanometer $G$ shows zero deflection. If the internal resistance of batteries $A$ and $B$ is negligible,then the value of resistance $R$ is ....... $\Omega$.

Four ammeters with identical internal resistances $r$ and a resistor of resistance $R$ are connected to a current source as shown in the figure. It is known that the reading of the ammeter $A_1$ is $I_1 = 3\ A$ and the reading of the ammeter $A_2$ is $I_2 = 5\ A$. Determine the ratio of the resistances $R/r$.

The charge accumulated on the capacitor connected in the following circuit is . . . . . . $\mu C$ (Given $C=150\ \mu F$)