Electronics and Communication Engineering - Exam Questions Papers

21. 

A heavily doped semiconductor exhibits a __________ such a device is called sensistors.

A. negative temperature coefficient of resistance
B. positive temperature coefficient of resistance till a particular value of temperature and then it shown negative temperature coefficient of resistance
C. positive temperature coefficient of resistance
D. none of the above

Answer: Option C

Explanation:

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22. 

Sampling frequency of
sin 100pt + cos 200pt + sin 100pt + cos 200pt is:

A. 100 Hz
B. 200 Hz
C. 400 Hz
D. none of these

Answer: Option D

Explanation:

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23. 

For real and odd signals, the Fourier series coefficient ak is __________ .

A. purely imaginary and even
B. purely real and even
C. purely imaginary and odd
D. purely real and odd

Answer: Option C

Explanation:

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24. 

The magnitude of frequency response of an underdamped second order system is 5 at 0 rad/sec and peaks to at 52rad/sec. The transfer function of the system is

A.
B.
C.
D.

Answer: Option A

Explanation:

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25. 

Who developed the concept of time varying electric field producing a magnetic field?

A. Gauss
B. Faraday
C. Hertz
D. Maxwell

Answer: Option B

Explanation:

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