Electronics and Communication Engineering - Exam Questions Papers

41. 

For a message signal m(t) = cos (2pfmt) and the carrier frequency fc, which of the following represents a single side band (SSB) signal?

A. cos (2pfmt) cos (2pfct)
B. cos (2pfct)
C. cos [2p(fc + fm) t]
D. [1 + cos (2pfmt) cos (2pfct)]

Answer: Option C

Explanation:

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42. 

In the circuit shown below, the op-amp is ideal, the transistor has VBE = 0.6 V and β = 150. Decide whether the feedback in the circuit is positive or negative and determine the voltage V at the output of the op-amp

A. Positive feedback, V = 10 V
B. Positive feedback, V = 0 V
C. Negative feedback, V = 5 V
D. Negative feedback, V = 2 V

Answer: Option D

Explanation:

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43. 

Which of the following addressing modes is used in the instruction PUSH B?

A. Direct
B. Register
C. Register Indirect
D. Immediate

Answer: Option C

Explanation:

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44. 

Consider a silicon p-n junction at room temperature having the following parameters:
Doping on the n-side = 1 x 1017 cm-3
Depletion width on the n-side = 0.1 μm
Depletion width on the p-side = 1.0 μm
Intrinsic carrier concentration = 1.4 x 1014F. cm-1.
Thermal voltage = 26mV
Permittivity of free space = 8.85 x 10-14F. cm-1.
Dielectric constant of silicon = 12. The peak electric field in the device is

A. 0.15 MV.com-1, directed from p-region to n-region
B. 0.15 MV.com-1, directed from n-region to p-region
C. 1.80 MV.com-1, directed from p-region to n-region
D. 1.80 MV.com-1, directed from n-region to p-region

Answer: Option B

Explanation:

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45. 

A single turn loop is situated in air, with a uniform magnetic field normal to its plane. The area of the loop is 5 m2 and the rate of change of flux density is 2 Wb/m2/s. What is the emf appearing at the terminals of the loop?

A. -5 V
B. -2 V
C. -0.4 V
D. 0 V

Answer: Option A

Explanation:

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