The value of current $I$ in the electrical circuit as given below,when potential at $A$ is equal to the potential at $B$,will be . . . . . . $A$.

The figure shows a network of four resistances and three batteries. The current through the branch $CF$ is ............... $A$.

In the cube shown,current $i$ enters at $H$ and leaves at $C$. If $i_{AB} = \frac{i}{6}$,$i_{DC} = \frac{2i}{3}$,$i_{HA} = \frac{i}{2}$,$i_{GF} = \frac{i}{6}$,and $i_{HE} = \frac{i}{6}$,choose the branch in which the current is zero.

The resistances of the four arms $P, Q, R$ and $S$ in a Wheatstone's bridge are $10 \, \Omega$, $30 \, \Omega$, $30 \, \Omega$ and $90 \, \Omega$, respectively. The e.m.f. and internal resistance of the cell are $7 \, V$ and $5 \, \Omega$ respectively. If the galvanometer resistance is $50 \, \Omega$, the current drawn from the cell will be ............... $A$.

The effective resistance between points $A$ and $B$ is ............... $\Omega$.

The resistance of each arm of the Wheatstone bridge is $10 \, \Omega$. A resistance of $10 \, \Omega$ is connected in series with a galvanometer. Then, the equivalent resistance across the battery will be: