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)
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)
EM.15) A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls find cut off wavelength for dominant mode
(a) 4 cm
(b) 1 cm
(b) 2 cm
(b) 8 cm
Answer is (a)
EM.16) Poynting Vector signifies
(a)current density vector producing electrostatic field
(b)power density vector producing electromagnetic field
(c) current density vector producing electromagnetic field
(d) power density vector producing electrostatic field
Answer is (b)
EM.17) The VSWR can have any value between
(a)0 & infinity
(b)-1 & 1
(c) -1 & infinity
(d)1 & infinity
Answer is (d)
EM.18) The unit of $\nabla \times H $ is
(a)$Ampere-Metre$
(b)$Ampere/Metre^{2}$
(c)$Ampere/Metre$
(d)none of above
Answer is (b)
EM.19) When the separation between two charges increases, the electric potential energy of charges
(a) increases
(b) decreases
(c) remains the same
(d) may increase or decrease
Answer is (b)
EM.20) A hollow rectangular waveguide acts as a ________
(a) high pass filter
(b) low pass filter
(c) band pass filter
(d) band stop filter
Answer is (a)
EM.21) The velocity of electromagnetic wave in a good conductor is
(a)$3 \times 10^8 m/s$
(b)more than $3 \times 10^8 m/s$
(c)very low
(d)high
Answer is (c)
EM.22)Solution to Maxwell's equation for waveguides in Transverse Electric Magnetic Mode (TEM) is
(a)$E_z = 0,H_z= 0$
(b)$E_z \neq 0,H_z = 0 $
(c)$E_z = 0,H_z \neq 0$
(d)$E_z\neq 0, H_z \neq 0$
Answer is (a)
EM.23) Radiation intensity of a dipole depends strongly on frequency. If at a
frequency f, the intensity of radiation is 'I'. Then at a frequency of f/2, the
intensity will be
(a) I/2
(b) I/4
(c) I/8
(d) None
of these
Answer is (a)
EM.24) Which of the following should dominant wave have?
(a) Lowest
cut off frequency
(b)
Highest cut off frequency
(c) No
attenuation
(d) No
phase shift
Answer is (a)
EM.25) The electric
field of the incident wave is $E_i = E_0 cos(\omega t - \beta_z) a_y$, where $\omega = 3\times10^{22}\pi$ and $\beta = 10\pi$. The electric field of the transmitted
wave $E_t$ is given by
(a) (2/3)
Eo cos(wt-beta along z-direction) along x-direction
(b) (2/3)
Eo cos(wt-2beta along z-direction) along x-direction
(c) (1/2)
Eo cos(wt-beta along z-direction) along y-direction
(d) (1/2)
Eo cos(wt-3 beta along z-direction) along y-direction
Answer is ()
EM.26) The Depth of penetration of EM wave in medium having
conductivity σ at a frequency of 1 MHz is 25 cm. The depth of penetration at a
frequency of 4 MHz will be
(a) 6.25
cm
(b) 12.50
cm
(c) 50 cm
(d) 100 cm
Answer is ()
EM.27)The correct relationship between group velocity Vgr and
phase velocity Vph is:
(a)Vgr×Vph =c
(b)Vgr × Vph = c^2
(c)Vgr × Vph = √c
(d)Vgr ×Vph= c^2/2
Answer is ()
EM.28) The phase velocity of an electromagnetic wave
propagating in a hallow metallic rectangular waveguide in TE(10) mode is
(a) equal
to its group velocity
(b) less
than the velocity of light in free space
(c) equal
to the velocity of light in free space
(d)
greater than the velocity of light in free space
Answer is ()
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