The circuit shown has $3$ identical light bulbs $A, B, C$ and $2$ identical batteries $E_1, E_2.$ When the switch is open, $A$ and $B$ glow with equal brightness. When the switch is closed:

The graphs between current $\left(I\right)$ and voltage $\left(V\right)$ for three linear resistors $1$, $2$ and $3$ given below.

If $R_1, R_2$ and $R_3$ are the resistances of these resistors, then which one of the following is correct?

What is the current in the $4 \mathrm{\Omega }$ resistor when switch $S_1$ is open and switch $S_2$ is closed in the given circuit?

The net resistance between point $P$ and $Q$ in the circuit shown in figure is