Question Answer Set 15-28
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 ()
