Two positives ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be (e being the charge on an electron)

A square surface of side L meter in the plane of the paper is placed in a uniform electric field $$E$$(volt/m) acting along the same plane at an angle $$\theta $$ with the horizontal side of the square as shown in figurre.


The electric flux linked to the surface, in units of volt m is

Three concentric spherical shells have radii a, b and c (a < b < c) anf have surface charge densities $$\sigma $$, $$-$$$$\sigma $$ and $$\sigma $$ respectively. If V_A, V_B and V_C denote the potentials of the three shells, then, for c = a + b, we have

The electric potential at a point (x, y, z) is given by V = $$-$$x²y $$-$$ xz³ + 4

The electric field at that point is