Electricity and Magnetism Answers

Explain the working of a velocity selector.

Obtain an expression for the potential at a point near an infinitely long charged wire.

A parallel plate capacitor having rectangular
plates of area of cross-section 6.45 x 10^-4 m² each is kept in free space. The separation
between the plates is 1.5 x 10^-3 m and a
voltage of 15 V is applied across these plates. Calculate the capacitance of the capacitor. If a material of dielectric constant 6.0 is introduced in the region between the two plates, calculate the capacitance and the
electric displacement D .

Using Gauss's law, obtain expressions
for electric field at a point (i) outside, and
(ii) inside a spherical charge distribution.

A current of 2.5 A flowing in a solenoid having
self-inductance 3.8 H is reduced steadily to
zero in 1.0 ms. Calculate the magnitude of the
back emf of the solenoid while the current is
being switched off.

What is the basic difference in the nature of
the electric fields produced by static charges
and those induced by changing magnetic
fields ?

In the Bohr model, the electron of a hydrogen
atom moves in a circular orbit of radius
5.3 x 10^-11 m with a speed of 2.2 x 10^6 ms^-1. Determine its frequency and the current in the orbit.

The magnetic field at the centre of a solenoid
of length 2.5 m and diameter 0.8 m is
0.5 tesla. Calculate the energy stored in the
field of the solenoid.

Two parallel plates which have a cross-sectional area of 100 cm², carry an equal
and opposite charge of 1.0×10^-7 C. The space between the plates is filled with a dielectric material and the electric field within the dielectric is 2.3 x 10^5 Vm^-1. If the electric field across the plates without the dielectric is given by E0 = sigma/aphselonot sigma being the surface charge density of the plates, calculate the dielectric constant of the dielectric.

Explain the mechanism of polarisation in
dielectrics made up of non-polar molecules and
dielectrics made up of polar molecules.