Electricity and Magnetism Answers

The number density of electrons in a metal is 28 3 9.64 10 m− × . 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?

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

Determine the effective capacitance of the following combination of capacitors given that the capacitance of each capacitor is 3 μF.

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?

Three charges q, 2q and q are to be placed on a straight wire of length 10 m.
Determine the positions where the charges should to be placed so that the
electrostatic potential energy of the system is a minimum.

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.