# Electronics and Communication Engineering - Exam Questions Papers

41.

A junction FET, can be used as a voltage variable resistor

 A. at pinch-off condition B. beyond pinch-off voltage C. well below pinch-off condition D. for any value of VDS

Explanation:

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42.

A fully charged mobile phone with a 12 V battery is good for a 20 minute talktime. Assume that, during the talk time, the battery delivers a constant current of 2 A and its voltage drops linearly from 12 V to 10 V as shown in the figure. How much energy does the battery deliver during this talk time?

 A. 220 J B. 12 kJ C. 13.2 kJ D. 14.4 kJ

Explanation:

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43.

In a material, the Fermi level is located between the centre of the forbidden band and the conduction band. Then what is that material?

 A. A p-type semiconductor B. An n-type semiconductor C. An intrinsic semiconductor D. An insulator

Explanation:

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44.

Consider an SSB signal when the modulating signal is x(t). Let x(t) represents the complex conjugate of x(t) and is its Hilbert transform. The envelope of SSB signal is:

 A. B. C. x(t) D.

Explanation:

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45.

Consider two independent random variables x and y with identical distributions. The variables X and Y take 0, 1 and2 with probabilities and respectively. What is the conditional probability P(X + Y = 2| X - Y = 0)?

 A. 0 B. C. D. 1