Electronics and Communication Engineering - Exam Questions Papers

31. 

Which one of the following type of negative feedback increases the input resistance and decreases the output resistance of an amplifier?

A. Current series feedback
B. Voltage series feedback
C. Current shunt feedback
D. Voltage shunt feedback

Answer: Option B

Explanation:

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32. 

A load ZL = RL + jXL is to be matched using an ideal transformer to generator of internal impedance ZS = RS + jXS. The ratio of transformer required is __________ .

A. |ZS|/|ZL|
B. RL/RS
C. RL/ZS
D. |ZL|/RS

Answer: Option A

Explanation:

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33. 

An AC source or RMS voltage 20V with internal impedance Zs = (1 + 2j) Ω feeds a load of impedance ZL = (7 + 4j) Ω in the figure below. The reactive power consumed by the load is

A. 8 VAR
B. 16 VAR
C. 28 VAR
D. 32 VAR

Answer: Option A

Explanation:

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34. 

Electric dipole is located at origin in a medium with εr = 6, has a moment P = (4ax - 2ay + az ) nC. Then potential at (2, 4, 4) is:

A. 0.062
B. 0.027
C. 0.042
D. 0.072

Answer: Option B

Explanation:

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35. 

Voice signal band limited to 3.4 KHz is sampled and pulse code modulated using 64 quantization levels. Ten such signals are time division multiplexed using one 5-bit synchronizing word every alternate frame. The minimum channel bandwidth required for transmission of the TDM signal is

A. 100 KHz
B. 200 KHz
C. 50 KHz
D. 150 KHz

Answer: Option B

Explanation:

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