A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are :

$\mathrm{P}$ and $\mathrm{Q}$ are two square plates of copper having the same thickness. The current is flowing through them, as shown. The side of $\mathrm{Q}$is twice the side of$\mathrm{P}$. Then :

A carbon resistor has coloured bands as shown in figure. The resistance of the resistor is

: