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:

A battery of $10 \mathrm{V}$ and negligible internal resistance is connected across the diagonally opposite corner of a cubical network consisting of $12$ resistors each of resistance $1 \mathrm{\Omega }$. The total current $I$ in the circuit external to the network is:

Consider the circuit below. The bulb will light up if:

Two bulbs, one of $200 \mathrm{W}$ and the other of $100 \mathrm{W}$, are connected in series with a $100 \mathrm{V}$ battery which has no internal resistance. Then,

Figure $\left(\mathrm{a}\right)$ below shows a Wheatstone bridge in which $P,Q,R,S$ are fixed resistances, $G$ is a galvanometer and $B$ is a battery. For this particular case, the galvanometer shows zero deflection. Now, only the positions of $B$ and $G$ are interchanged, as shown in figure $\left(\mathrm{b}\right)$. The new deflection of the galvanometer-