Electronics and Communication Engineering - Exam Questions Papers

26. 

In the slotted line measurement for standing wave Ratio (SWR), the distance between the two 3-dB points is Δd and λ' the wavelength along the transmission line. SWR of the transmission system is given by

A.
B.
C.
D.

Answer: Option C

Explanation:

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27. 

Why npn-transistors are preferred over pnp-transistors?

A. Leakage current in npn-transistors is less than pnp-transistors
B. Mobility of majority carrier in npra-transistors is greater than the mobility of majority carrier in pnp-transistors
C. Bias voltage required in npn is less than in/wp-transistors
D. Bias voltage required in npn is greater than in pnp-transistors

Answer: Option B

Explanation:

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28. 

For parallel plane waveguides, which is the mode with lowest cut-off frequency?

A. TE10
B. TM10
C. TEM
D. TE11

Answer: Option A

Explanation:

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29. 

Which of the following conditions must be satisfied for a transistor to remain under saturation?

  1. Its collector to base junction should be under forward bias.
  2. Its collector to base junction should be under reverse bias.
  3. Its emitter to base junction should be under reverse bias.
  4. Its emitter to base junction should be under forward bias.
Select the correct answer from the codes given below:

A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 1 and 4

Answer: Option D

Explanation:

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30. 

Voltage 1 + 2 sin ωt is applied to the circuit shown below:

The capacitor C and diode D can be considered ideal. RL is very large resistance. Then the magnitude of the average voltage across RL is __________ volt.

A. 0 volt
B. 2 volts
C. -2 volts
D. -3 volts

Answer: Option C

Explanation:

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