Electricity and Magnetism Answers

Explain the mechanism of polarization in polar and non polar dielectrics.

The number density of electrons in a metal is 9.64×1028m−3 . What is the drift
velocity of electrons in a wire made up of this metal when a current of 4A flows in
it given that its cross-sectional area is 2.0 mm2? How long will it take for an
electron to travel a distance of 0.10 m in this wire?

A parallel plate capacitor is made of two rectangular plates of area 1.0 m^2 and the
separation between plates is 2.0 mm. A voltage of 100 V is applied across the
plates. Calculate the capacitance of the capacitor if a dielectric material of dielectric
constant 3.0 is introduced between the plates. What is the charge stored on each
plate of the capacitor?

Two large parallel conducting plates carrying equal and opposite charges on their
surfaces facing each other are placed at a distance of 0.75 m. An electron placed at
some point between the plates experiences an electrostatic force of 4.8 × 10^-16 N.
Calculate the magnitude of the electric field at the position of the electron between
the plates. Also determine the potential difference between the plates.

Using Maxwell’s equations in free space, derive the wave equation for the z-component of the electric field vector.

Metallic iron contains approximately 1029 atoms per cubic meter. The magnetic moment of each iron atom is 1.8 × 10−23 Am−1. If all the dipoles were perfectly aligned what would be the magnetisation M and the magnetic moment of a bar 10 cm long and 1cm2 in cross-section?

An electron and a proton, having the same kinetic energy, enter a region of uniform magnetic field moving perpendicular to the field. Calculate the ratio of the radii of their circular paths in the field.

Two long, straight, parallel wires 24 cm apart carry currents of I1 = 30A andI2 = 20A in the same direction. Determine the magnetic field in the plane of the twowires at a point halfway between the wires.

Twolargeparallelconductingplatescarryingequalandoppositechargesontheir surfaces facing each other are placed at a distance of 0.75 m. An electron placed at some point between the plates experiences an electrostatic force of 4.8 × 10-16 N. Calculate the magnitude of the electric field at the position of the electron between the plates. Also determine the potential difference between the plates.

A positron of mass m moving with speed Vo enters into a region of uniform magnetic field B ,(produce out of the plane of paper) . The width of the region of magnetic field is " (3mVo)/(2eB)". Find the time spent by the particle in magnetic field if "theta" is nearly 90°.
(a) (2πm)/(3Be). (b). (3πm)/2Be
(c) (2πm)/eB. (d). Infinite