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....$V$

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

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.....$volt$

In a parallel plate air capacitor, a cathode beam comprising $n = 10^6$ electrons is emitted with a velocity $v_0 = 10^8\ m/s$ into the space between the plates. The potential difference between the plate is $\phi  = 400\ V$ ,the seperation between the plates is $d = 2\ cm$ and the area of each plate is $l^2 = 100\ cm^2$ . The deflection of the electron beam, is ........... $mm$

Four dipoles having charge $ \pm e$ are placed inside a sphere. The total flux of ${\vec E}$ coming out of the sphere is 

Charge $q$ is uniformly distributed over a thin half ring of radius $R$. The electric field at the centre  of the ring is