EM.1) Two spheres having the radius 'r' and 'R' are joined by a conducting wire. Each of the sphere has been given a charge Q. Now,
(a) both spheres will have equal potential
(b) larger sphere will have lesser potential
(c) larger sphere will have greater potential
(d) cannot be answered as data provided is insufficient
Answer is (a)
EM.2)When an electromagnetic wave is reflected at an angle from the wall , their wavelength along the wall is:
(a) same as in free space
(b) same as the wavelength perpendicular to wall
(c) shortened because of doppler effect
(d) greater than in the actual direction of propagation
Answer is (d)
= sqrt(200*50) = sqrt(10000)
= 100 Ω
EM.2)When an electromagnetic wave is reflected at an angle from the wall , their wavelength along the wall is:
(a) same as in free space
(b) same as the wavelength perpendicular to wall
(c) shortened because of doppler effect
(d) greater than in the actual direction of propagation
Answer is (d)
EM.3) If the static magnetic flux density is B, then
(a) curl of B = 0
(b) divergence of B = 0
(a) curl of B = 0
(b) divergence of B = 0
(c) curl of B = J
(d) divergence of B = J
Answer is (b)
EM.4) If vectors A & B are conservative then
(a) A x B is solenoidal
(b) A x B is conservative
(c) A + B is solenoidal
(d) A - B is solenoidal
Answer is (a)
Answer is (a)
EM.5) Kirchoff's current law is implicit in the expression
(a) divergence of D = volume charge density
(b) divergence of B = 0
(c) surface integral of (J.ds) = 0
(d) none of these
Answer is (c)
(d) none of these
Answer is (c)
EM.6) Find the nature of given vector field defined by vector :A = yz i^ + zx j^ + xy k^
(a) neither solenoidal nor irrotational
(b) solenoidal & irrotational
(c) only solenoidal
(d) only irrotational
Answer is (b)
Answer is (b)
EM.7) Function f(x+v(t)) represents which of the following?
(a) a stationary wave
(b) a wave motion in forward direction
(c) a wave motion in reverse direction
(d) none of the above
Answer is (c)
EM.8)$ \nabla \cdot (\nabla \times A)$ equals
(a) 0
(a) 0
(b) 1
(c) infinite
(d) none of above
Answer is (a)
EM.9) Zl = 200Ω and it is desired that Zi = 50Ω . Expected characteristic impedance of the quarter wave transformer is
(a) 100 Ω
(b) 40 Ω
(b) 40 Ω
(c) 10000 Ω
(d) 4 Ω
(d) 4 Ω
Answer is (a)
Explanation
Z0 = sqrt(Zl*Zi)= sqrt(200*50) = sqrt(10000)
= 100 Ω
EM.10) Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 10^14 Hz in glass. Assume velocity of light as 3 x 10^8 m/sec in vacuum.
(a) 4 μm
(b) 3 μm
(b) 3 μm
(c) 2 μm
(d) 1 μm
(d) 1 μm
Answer is (c)
EM.11) A plane electromagnetic wave travels in a dielectric medium of relative permittivity 9. Relative to free space, the velocity of propagation in the dielectric is
(a) increased by a factor of 9
(b) increased by a factor of 3
(c) unchanged
(d) reduced by a factor of 1/3
Answer is (d)
Answer is (d)
EM.12) For the vector function, vector A = xy2 i + yz2 j + 2xz k . Calculate ∫A.dl where the limits of the integral is a straight line joining the points (0,0,0) to (1,2,3)
(a) 2Π
(b) 8Π
(c) 16
(d) 13
(d) 13
Answer is (c)
EM.13) In a uniform electric field, field lines & equipotentials
(a) are parallel to one another
(b) intersect at 45°
(c) intersect at 30°
(d) orthogonal
Answer is (d)
EM.14) When a charge is given to a conductor
(a) it distributes uniformly all over the surface
(b) it distributes uniformly all over the volume
(c) it distributes on the surface , inversely proportional to radius of curvature
(d) it stays where it was placed
(d) it stays where it was placed
Answer is (a)
