Electronics and Communication Engineering - Exam Questions Papers

1. 

The minimum energy of a photon required for intrinsic excitation is equal to

A. energy of bottom of conduction band
B. energy of top of valence band
C. forbidden gap energy
D. Fermi energy

Answer: Option C

Explanation:

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2. 

The circuits with active pull up are preferred because of their stability for

A. wired - AND operation
B. wired - OR operation
C. bus operated system
D. reasonable dissipation and speed of operation

Answer: Option A

Explanation:

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3. 

A scheme shown below is to generate a wide band FM modulate signal.

Narrow band FM has carrier frequency = 400 KHz
Deviation ratio = 0.2
Wide band FM has carrier frequency = 100 MHz
Deviation ratio = 6
Local oscillator frequencies can be

A. 88 MHz, 112 MHz
B. 96 MHz, 104 MHz
C. 92 MHz, 108 MHz
D. 90 MHz, 110 MHz

Answer: Option A

Explanation:

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4. 

How many maximum number of functions can be defined with two symbols which are Boolean in nature:

A. 4
B. 8
C. 2
D. 16

Answer: Option D

Explanation:

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5. 

The characteristic equation of a control system is given as s4 + 4s3 + 4s2 + 3s + K = 0.
What is the value of K for which this system is marginally stable?

A.
B.
C.
D.

Answer: Option D

Explanation:

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