Four $4 \Omega$ resistors are connected together along the edges of a square. A 12 V battery with internal resistance of $2 \Omega$ is connected across a pair of the diagonally opposite corners of the square. The power dissipated in the circuit is

A conducting wire of cross-sectional area $1 \mathrm{~cm}^2$ has $3 \times 10^{23}$ charge carriers per $\mathrm{m}^3$. If wire carries a current of 24 mA , then drift velocity of carriers is

The total current supplied to the following circuit by the battery is

A cylindrical wire $P$ has resistance $10 \Omega$. A second wire $Q$ has length and diameter half that of $P$. If the material of both the wires is same, then resistance of wire $Q$ is