Electromagnetic Theory - Study Mode
[#6] A plane electromagnetic wave of frequency ω is incident normally on an air-dielectric interface. The dielectric is linear, isotropic, non-magnetic and its refractive index is n. The reflectance (R) and transmittance (T) from the interface are
Correct Answer
(A) $$R = {left( {frac{{n - 1}}{{n + 1}}}
ight)^2},,T = frac{{4n}}{{{{left( {n + 1}
ight)}^2}}}$$
[#7] A conducting sphere of radius R has charge +Q on its surface. If the charge on the sphere is doubled and its radius is halved, the energy associated with the electric field will
Correct Answer
(B) increase eight times
[#8] Four charges are placed at the four corners of a square of side a as shown in the figure. The electric dipole moment of this configuration is
Correct Answer
(C) $$overrightarrow {x08f{p}} = - qa{x08f{hat i}} - qa{x08f{hat j}}$$
[#9] Far away from any of the resonance frequencies of a medium, the real part of the dielectric permittivity is
Correct Answer
(A) always independent of frequency
[#10] A circular disc of radius a on the XY-plane has a surface charge density $$sigma = frac{{{sigma _0}rcos heta }}{a}.$$ xa0 The electric dipole moment of this charge distribution is
Correct Answer
(B) $$frac{{{sigma _0}pi {a^3}}}{4}{x08f{hat x}}$$