Show that, if there are any unbalanced, static charges on an isolated conductor, they

must reside on its surface.

Two concentric thin metallic spheres having radii 30 cm and 20 cm carry 10 µC and

5 µC, charges respectively. Calculate the electric potential at a distance of 25 cm

from the centre of the spheres.

What is the difference between ohmic conductor and non-ohmic conductor? Give

one example each and draw their IV characteristic curves.

If the space between the plates of a capacitor is filled will a dielectric material, does

it affect the value of capacitance? Justify your answer.

A long, straight wire of radius 5.0 mm carries a current of 20A. i) Calculate the magnetic field at the surface of the wire, and ii) calculate the perpendicular distance, from the axis of the wire, at which the magnitude of magnetic field will be half of

its value at the wire surface.

The line density of charge in a wire is 0.2 Cm⁻¹. If this wire is symmetrically enclosed, along its length, by a cylindrical surface of radius 1 m and length 1.5 m, calculate i) the electric flux through the cylindrical surface, and ii) the electric field

at the curved surface of the cylinder.

Using Maxwell’s equations in free space, derive the wave equation for the

electric field vector. Obtain the conditions under which the following time varying electric and magnetic fields satisfy Maxwell’s equations in vacuum with no source charges or currents:

E = kˆ E0 sin ( y − vt)

B = ˆi B0 sin ( y − vt)

where E₀ and B₀ are constant.