In the following diagram, the work done in moving a point charge from point $P$ to points $A, B$ and $C$ are $W_A, W_B$ and $W_C$ respectively. Then ( $A, B, C$ are points on semi-circle and point charge $q$ is at the centre of semi-circle)

Four condensers each of capacitance $8 \mu \mathrm{~F}$ are joined as shown in the figure. The equivalent capacitance between the points $A$ and $B$ will be

A steady current is flowing in a metallic conductor of non-uniform cross-section. The physical quantity which remains constant is

The resistance between points $A$ and $C$ in the given network is