Two charges $q_1$ and $q_2$ are placed $30\,cm$ apart, as shown in the figure. A third charge $q_3$ is moved along the arc of a circle of radius $40\,cm$ from $C$ to $D$. The change in the potential energy of the $\frac{{{q_3}}}{{4\pi \,{ \in _0}}}k$ , where $k$ is

The four capacitors, each of $25\,\mu F$ are connected as shown in Fig. The $dc$ voltmeter reads $200\,V$. The charge on each plate of capacitor is

A hollow conducting sphere is placed in a electric field proudced by a point charge placed at $P$ as shown in figure. Let $V_A, V_B, V_C$ be the potentials at points $A, B$ and $C$ respectively. Then

Four capacitors with capacitances $C_1 = 1\,μF, C_2 = 1.5\, μF, C_3 = 2.5\, μF$ and $C_4 = 0.5\, μF$ are connected as shown and are connected to a $30\, volt$ source. The potential difference between points $B$ and $A$ is….$V$

Consider a cube of uniform charge density $\rho$. The ratio of electrostatic potential at the centre of the cube to that at one of the corners of the cube is