Electromagnetic Theory - Study Mode
[#41] Consider the following three independent cases: i. Particle A of charge +q moves in free space with a constant velocity $$overrightarrow {x08f{v}} $$ (v ≪ speed of light). ii. Particle B of charge +q moves in free space in a circle of radius R with same speed v as In case i. iii. Particle C having charge -q moves as in case ii. If the powers radiated by A, B and C are P A , P B and P C respectively then
Correct Answer
(B) P A = 0, P B = P C
[#42] An infinitely long wire carrying a current $$Ileft( t
ight) = {I_0}cos left( {omega t}
ight)$$ xa0 xa0is placed at a distance a from a square loop of side a as shown in the figure. If the resistance of the loop is R, then the amplitude of the induced current in the loop is
Correct Answer
(A) $$frac{{{mu _0}}}{{2pi }} cdot frac{{a{I_0}omega }}{R}ln 2$$
[#43] A large circular coil of N turns and radius R carries a time varying current $$I = {I_0}sin left( {omega t}
ight).$$ xa0 A small circular coil of n turns and radius r(r ≪ R) is placed at the centre of the large coil such that the coils are concentric and coplanar. The induced emf in the small coil
Correct Answer
(D) lags the current in the large coil by $$frac{pi }{2}$$
[#44] A conducting loop L of surface area S is moving with a velocity $$overrightarrow {x08f{v}} $$ in a magnetic field $$overrightarrow {x08f{B}} left( {overrightarrow {x08f{r}} ,,t}
ight) = {B_0}{t^2},,{B_0}$$ xa0 xa0 is a positive constant of suitable dimensions. The emf
induced V emf in the loop is given by
Correct Answer
(D) $$ - intlimits_S {frac{{partial overrightarrow {x08f{B}} }}{{partial t}}.doverrightarrow {x08f{S}} } + ointlimits_L {left( {overrightarrow {x08f{v}} imes overrightarrow {x08f{B}} }
ight).doverrightarrow {x08f{L}} } $$
[#45] Unpolarized light falls from air to a planar air-glass interface (refractive index of glass is 1.5) and the reflected light is observed to be plane polarized. The polarization vector and the angle of incidence θ i are
Correct Answer
(C) perpendicular to the plane of incidence and θ i = 56°