Exercise: Electromagnetic Field Theory

Questions for: Electromagnetic Field Theory

A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.
A:
49
B:
47.33
C:
50.33
D:
50
Answer: B

Since, wave is attenuated hence β = 0

and Take, dominant mode m = 1,

n = 0

.

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The phase angle corresponding to λ/4 in a standing-wave pattern is
A:
30°
B:
90°
C:
135°
D:
180°
Answer: B

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Consider a 300 Ω, quarter wave long at 1 GHz transmission line as shown in figure. It is connected to a 10 V, 50 Ω source at one end is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is
A:
10 V
B:
5 V
C:
60 V
D:
60/7 volt
Answer: A

γ = a + jβ a = 0 γ = jβ

Propagating wave

v = VI e-rz + VR erz

No change in the voltage at the open end it will same,

vr = 10 volt.

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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:
B:
C:
D:
Answer: A

I ∝ f.

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The velocity of electromagnetic wave in a good conductor is
A:
3 x 108 m/s
B:
more than 3 x 108 m/s
C:
very low
D:
high
Answer: C

, for good conductor εr >> 1.

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