What is the current $I$ (in $A$) flowing through the given circuit?

In the circuit shown,the current through the $4\,\Omega$ resistor is $1\,A$ when the points $P$ and $M$ are connected to a d.c. voltage source. The potential difference between the points $M$ and $N$ is ............... $V$.

The potential difference between $A$ and $B$ in the figure is ................... $V$.

In the given figure,each plate of the capacitor with capacitance $C$ has a charge. Find the charge on the capacitor.

When a wire of uniform cross-section $a$,length $l$ and resistance $R$ is bent into a complete circle,what is the resistance between any two diametrically opposite points?

$A$ resistor ${R_1}$ dissipates the power $P$ when connected to a certain generator. If the resistor ${R_2}$ is put in series with ${R_1}$,the power dissipated by ${R_1}$