Questions and answers for exam Preparation

MCQs

Total Questions : 33 | Page 3 of 4 pages

Question 21. A function y = 5x2 +10 x is defined over an open interval x = (1, 2) . At least at one point in this interval, dy/dx is exactly

Discuss Question

Answer: Option B. -> 25

-NA-

Question 22. Two systems with impulse responses h1 (t) and h2 (t) are connected in cascade. Then the overall impulse response of the cascaded system is given by

product of h1 (t) and h2 (t)
sum of h1 (t) and h2 (t)
convolution of h1 (t) and h2 (t)
subtraction of of h2 (t) and h1 (t)

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Answer: Option C. -> convolution of h1 (t) and h2 (t)

-NA-

Question 23. The flux density at a point in space is given by B = 4 xax + 2kyay + 8 az Wb/m2. The value of constant k must be equal to

-2
-0.5
+0.5
+2

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Answer: Option A. -> -2

-NA-

Question 24. A single-phase transformer has no-load loss of 64 W, as obtained from an open-circuit test. When a
short-circuit test is performed on it with 90% of the rated currents flowing in its both LV and HV
windings, the measured loss is 81 W. The transformer has maximum efficiency when operated at

50.0% of the rated current.
64.0% of the rated current.
80.0% of the rated current.
88.8% of the rated current.

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Answer: Option C. -> 80.0% of the rated current.

-NA-

Question 25. A source vs (t) = V cos 100 Ï€t has an internal impedance of (4 + j3)â„¦ . If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in â„¦ should be

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Answer: Option C. -> 5

-NA-

Question 26. A single-phase load is supplied by a single-phase voltage source. If the current flowing from the load to the source is 10âˆ -150oA and if the voltage at the load terminals is 100âˆ 60o V, then the

load absorbs real power and delivers reactive power.
load absorbs real power and absorbs reactive power.
load delivers real power and delivers reactive power.
load delivers real power and absorbs reactive power.

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Answer: Option B. -> load absorbs real power and absorbs reactive power.

-NA-

Question 27. A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the
first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches
irrespective of the state of the other switch. The logic of switching of the bulb resembles

an AND gate
an OR gate
an XOR gate
a NAND gate

Discuss Question

Answer: Option C. -> an XOR gate

-NA-

Question 28. The angle Î´ in the swing equation of a synchronous generator is the

angle between stator voltage and current.
angular displacement of the rotor with respect to the stator.
angular displacement of the stator mmf with respect to a synchronously rotating axis.
angular displacement of an axis fixed to the rotor with respect to a synchronously rotating axis.

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Answer: Option D. -> angular displacement of an axis fixed to the rotor with respect to a synchronously rotating axis.

-NA-

Question 29. For a periodic signal v(t) = 30 sin100t + 10 cos 300t + 6 sin (500t + Ï€ / 4) , the fundamental frequency in rad/s is

100
300
500
1500

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Answer: Option A. -> 100

-NA-

Question 30. A band-limited signal with a maximum frequency of 5 kHz is to be sampled. According to the
sampling theorem, the sampling frequency in kHz which is not valid is

Discuss Question

Answer: Option A. -> 5

-NA-