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 ........... $mm$

Two charged spherical conductors of radii $R_1$ and $R_2$ are connected by a wire. The ratio of surface charge densities of the spheres $\sigma _1/\sigma _2$ will be

The equivalent capacitance of the system of capacitors between $A$ and $B$ as shown in the figure

Angle between equipotential surface and lines of force is.......$^o$

The electric potential $V$ at any point $O$ ($x, y, z$ all in metre) in space is given by $V=4x^2\, volt$. The electric field at the point $(1\,m, 0, 2\,m)$ in $volt/meter$ is

A hollow conducting sphere is placed in an electric field produced 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