Electromagnetic Theory MCQs Question and Answer in Engineering Physics

An electric charge +Q is placed on the surface of a solid conduction sphere of radius a. The distance measured from the centre of the sphere is denoted as r. Then,

Consider a conducting loop of radius a and total loop resistance R placed in a region with a magnetic field B thereby enclosing a flux $${\phi _0}$$ . The loop is connected to an electronic circuit as shown, the capacitor being initially uncharged.

If the loop is pulled out of the region of the magnetic field at a constant speed u, the final output voltage V_out is independent of

A conducting sphere of radius R is placed in uniform electric field $${\overrightarrow {\bf{E}} _0}$$ directed along +Z-axis. The electric potential for outside points is given as $${V_{{\text{out}}}} = - {E_0}\left( {1 - \frac{{{R^3}}}{{{r^3}}}} \right)r\cos \theta ,$$      where r is the distance from the centre and θ is the polar angle. The charge density on the surface of the sphere is

A laser beam of wavelength 600 nm with a circular cross-section having a radius of 10 mm fails normally on a lens of radius 20 mm and focal length 10 cm. The radius of the focussed spot is approximately

A current $$l$$ flows in the anticlockwise direction through a square loop of side a lying in the XOY plane with its centre at the origin. The magnetic induction at the centre of the square loop is

The electric (E) and magnetic (B) field amplitudes associated with an electromagnetic radiation from a point source behave at a distance r from the source as

An electron is accelerated from rest by 10.2 millionvolt. The percent increase in its mass is

A toroidal coil has N closely-wound turns. Assume the current through the coil to be $$l$$ and the toroid is filled with a magnetic material of relative permittivity $${\mu _r}.$$ The magnitude of magnetic induction $$\overrightarrow {\bf{B}} $$ inside the toroid, at a radial distance r from the axis, is given by

A particle of charge q, mass m and linear momentum $$\overrightarrow {\bf{p}} $$ enters an electromagnetic field of vector potential $$\overrightarrow {\bf{A}} $$ and scalar potential $$\phi .$$ The Hamiltonian of the particle is

Two magnetic dipoles of magnitude m each are placed in a plane as shown below. The energy of interaction is given by