1
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
A rectangular metal wave guide filled with a dielectric material of relative permittivity $${\varepsilon _r} = \,4$$ has the inside dimensions $$3.0\,cm\,\, \times \,\,1.2\,cm$$. The cut-off frequency for the dominant mode is
A
2.5 GHz
B
5.0 GHz
C
10.0 GHz
D
12.5 GHz
2
GATE ECE 2000
MCQ (Single Correct Answer)
+2
-0.6
A rectangular waveguide has dimensions $$1\,\,cm\,\, \times \,\,0.5\,\,cm$$. Its cut-off frequency is
A
5 GHz
B
10 GHz
C
15 GHz
D
20 GHz
3
GATE ECE 1993
MCQ (Single Correct Answer)
+2
-0.6
An optical fiber consists of a cylindrical dielectric rod of refractive index $$n_1$$, surrounded by another dielectric of refractive index $$n_2$$ where $$n_2$$ < $$n_1$$ as shown in the following Fig. If a ray is incident from air at angle i to the axis, then it undergoes total internal reflection at the interface AB if GATE ECE 1993 Electromagnetics - Waveguides Question 13 English
A
$$i\,\, \ge \,\,{\sin ^{ - 1}}\,\sqrt {{n_1}^2 - {n_2}^2} $$
B
$$i\,\, < \,\,{\sin ^{ - 1}}\,\sqrt {{n_1} - {n_2}} $$
C
$$i\,\, \le \,\,{\sin ^{ - 1}}\,\sqrt {{n_1}^2 - {n_2}^2} $$
D
$$i\,\, = \,\,{\sin ^{ - 1}}\,\sqrt {{n_1} - {n_2}} $$
4
GATE ECE 1990
MCQ (More than One Correct Answer)
+2
-0.6
Choose the correct statements.
For a wave propagating in an air filled rectangular wave guide
A
Guided wavelength is never less than the free space wavelength
B
Wave impedance is never less than the free space impedance.
C
Phase velocity is never less than the free space velocity
D
TEM mode is possible if the dimensions of the wave guide are properly chosen.
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