In the network shown in the figure,the potential difference across the $2R$ resistor is...... (The cell has an $emf$ $E$ and no internal resistance).

The potential difference between points $A$ and $B$ of the adjoining figure is

Two wires of the same material having lengths and radii in the ratio of $3:4$ and $3:2$ respectively are connected in parallel with a potential source of $6 \ V$. The ratio of currents flowing through them $I_1:I_2$ is . . . . . . .

Two long coaxial and conducting cylinders of radius $a$ and $b$ are separated by a material of conductivity $\sigma$ and a constant potential difference $V$ is maintained between them by a battery. Then the current per unit length of the cylinder flowing from one cylinder to the other is -

$A$ copper wire of radius $0.1 \text{ mm}$ and resistance $2 \text{ k}\Omega$ is connected across a power supply of $40 \text{ V}$. The number of electrons transferred per second between the supply and the wire at one end is

Find the current in the three resistors as shown in the following figure.