Answer carefully:
(a) Two large conducting spheres carrying charges `Q_(1)` and `Q_(2)` are brought close to each other. Is the magnitude of electrostatic force between them exactly given by `Q_(1),Q_(2)//4pi epsilon_(0)r^(2)`, where r is the distance between their centres?
(b) If Coulomb’s law involved `1//r^(3)` dependence (instead of would Gauss’s law be still true ?
(c) A small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point?
(d) What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if the orbit is elliptical?
(e) We know that electric field is discontinuous across the surface of a charged conductor. Is electric potential also discontinuous there?
(f) What meaning would you give to the capacitance of a single conductor?
(g) Guess a possible reason why water has a much greater dielectric constant (= 80) than say, mica (= 6).

Explanation

(a) No, because charge distributions on the spheres will not be uniform.
(b) No.
(c) Not necessarily. (True only if the field line is a straight line.) The field line gives the direction of acceleration, not that of velocity, in general.
(d) Zero, no matter what the shape of the complete orbit.
(e) No, potential is continuous.
(f) A single conductor is a capacitor with one of the ‘plates’ at infinity.
(g) A water molecule has permanent dipole moment. However, detailed explanation of the value of dielectric constant requires microscopic theory and is beyond the scope of the book.