Two point charges of + 3\(\mu \)C each are 100 cm apart.At what point on the line joining the charges will the electric field intensity be zero?

1

(a)

At the centre,since the electric field due to two charges is equal and opposite at this point.

Why should electrostatic field be zero inside a conductor?

1

(a)

Electric field lines do not pass through a conductor.Hence,  the interior of the conductor is free from the influence of the electric field

why do the electric field lines not form closed loops?

1

(a)

Electric field lines do not form closed loops because they are always directed from positive charge to negative charge.

The dimension of an atom are of the order of an angstrom. Thus, there must be large electric fields between the protons and electrons. Why, then is the electrostatic field inside a conductor zero?

1

(a)

The electric fields find the atoms to netural entity.As it is known that, electrostatic fields are caused by excess charges.However there is no excess charge on the inner surface of an isolated conductor.Therefore, electrostatic  field inside a conductor is zero.

A Metallic spherical shell has an inner radius R₁ and outer radius R_2.A charge Q is placed at the center of the spherical cavity.what will be surface charge density (i)the inner surface and (ii)the outer surface?

1

(a)

When a charge +Q is placed at the center of spherical cavity  Then, charge induced on the inner surface of a shell is -Q and charge induced on the outer surface of a shell is +Q

Therefore, surface charge density on inner surface of shell is \(\frac { -Q }{ 4\pi R_{ 1 }^{ 2 } } \) and outer surface of shell is  \(\frac { +Q }{ 4\pi R_{ 2 }^{ 2 } } \)