Electricity and Magnetism Answers

The capacitance of a parallel plate capacitor is increased by a factor of 7 when a dielectric
material fills the space between its plates. What is the relative permitivity of the dielectric
material? If this material is placed in between the plates of a cylindrical capacitor of outer
and inner radii 12 cm and 10 cm, respectively, calculate the capacitance per unit length of
the cylindrical capacitor.

State, giving reasons, whether the following statements are True or False:
(1)The electric field associated with a plane electromagnetic wave is given by
E = 50 cos (ωt – 10πx) zˆ Vm^–1
. Its wavelength is 0.5 m.

State, giving reasons, whether the following statements are True or False:
(1)Step-up transformer converts high voltage, low current into low voltage high current.

State, giving reasons, whether the following statements are True or False:
(1)Magnetisation of a paramagnetic material attains a saturation value at very low
temperatures and high magnetic fields.

State, giving reasons, whether the following statements are True or False:
(1) Gauss’s law for magnetism suggests that magnetic monopoles exist.

State, giving reasons, whether the following statements are True or False:
(1) An electron moves in a magnetic field of 1T with velocity 5.0 × 10^5
ms^–1
in the direction of
the magnetic field. The magnitude of the force experienced by the electron is 9.5 × 10^–14N.

State, giving reasons, whether the following statements are True or False:
(1) When a dielectric material is inserted between the parallel plates of a capacitor, the
electrostatic energy stored between the plates increases.

State, giving reasons, whether the following statements are True or False:
(1) In polar molecules, dipole moment exists even in the absence of an external electric field.

State, giving reasons, whether the following statements are True or False:
(1)The work done in taking a unit charge from one point to another in the electric field of a
charge + Q C depends on the path followed by the charge

State, giving reasons, whether the following statements are True or False:
(ii)An object is enclosed within a metallic spherical shell having surface charge + q C. The
object will carry charge – q C.