Force between $A$ and $B$ is $F$. If $75\%$ charge of $A$ is transferred to $B$ then force between $A$ and $B$ is

Two capacitors $C_1$ and $C_2 = 2\,C_1$ are connected in a circuit with a switch between them as shown in the figure. Initially the switch is open and $C_1$ holds charge $Q$. The switch is closed. At steady state, the charge on capacitors will be

An electric point charge $10^{-3}\,\mu C$ is placed at the origin $(0, 0)$ of $X-Y$ co- ordinate system. Two points $A$ and $B$ are situated at $(\sqrt 2, \sqrt 2)$ and $(2, 0)$ respectively. The potential difference between the points $A$ and $B$ will be.....$volt$

Two charged spheres of radii $R_1$ and $R_2$ having equal surface charge density. The ratio of their potential is

The plates of a parallel plate capacitor are charged up to $100\, volt$ . A $2\, mm$ thick plate is inserted between the plates, then to maintain the same potential difference, the distance between the capacitor plates is increased by $1.6\, mm$ . The dielectric constant of the plate is

A $2\,\mu F$ capacitor is charged to a potential $=10\ V$ . Another $4\,\mu F$ capacitor is charged to a potential $= 20\ V$ . The two capacitors are then connected in a single loop, with the positive plate of one connected with negative plate of the other. What heat is evolved in the circuit ?.........$\mu J$