UPSC_Exams > UPSC_Indian_Engineering_Services_Answer > UPSC_IES_EC_2014_Answer_Key_Question_par
ENGINEERING > ELECTRONICS
1) A periodic function satisfies Dirichlet's conditions. This implies that the function
A) is non-linearB) is not absolutely integrable
C) guarantees that Fourier series representation of the function existsD) has infinite number of maxima and minima within a period
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Answer : guarantees that Fourier series representation of the function exists


ENGINEERING > ELECTRONICS
2) Consider Fourier representation of continuous and discrete-time systems. The complex exponentials (ie., signals), which arise in such representation, have
A) same properties alwaysB) different properties always
C) non-specific propertiesD) mostly same properties
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Answer : same properties always


ENGINEERING > ELECTRONICS
3) If a dipole antenna has a radiation resistance of 73 ?, the loss resistance of 7 ? and the power gam is 16, then the directivity is
A) 17.53 dBB) 24.7 dB
C) 40 dB D) 14.6 dB
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Answer : 14.6 dB


ENGINEERING > ELECTRONICS
4) An LTI system is causal if and only if
A) h(t) = 0 for t < 0B) h(t) is finite for 0
C) h(t) is finite for t < 0D) h(t) is non-zero for all t
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Answer : h(t) = 0 for t < 0


ENGINEERING > ELECTRONICS
5) Let u[n] be the unit-step signal and
x[n]=(12)n u[n] + (-13)n u[n]
The region of convergence of z-transform of x[n] is
A) |z|>1⁄3B) 1 ⁄ 3 < |z| < 1⁄2
C) |z|>1⁄2D) |z|<1⁄2
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Answer : |z|>1⁄2


ENGINEERING > ELECTRONICS
6) If the z-transform of a sequence x[n] = {1,1,-1,-1} is X(z), then the value of X(1 ⁄2) is
A) 9B) 1.875
C) -1.125D) 15
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Answer : -1.125


ENGINEERING > ELECTRONICS
7) If the z-transform of a system is given by
H(z) =?+z-11+?z-1
where ? is real-valued, |?| |?|, then the system is
A) a low-pass filterB) a band-pass filter
C) an all-pass filterD) a high-pass filter
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Answer : a low-pass filter


ENGINEERING > ELECTRONICS
8) Consider a discrete random variable assuming finitely many values. The cumulative distribution function of such a random variable is
A) non-increasing functionB) non-decreasing function with finitely many discontinuities and assuming values less than one
C) non-decreasing function without discontinuitiesD) non-decreasing function assuming values larger than one
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Answer : non-decreasing function with finitely many discontinuities and assuming values less than one


ENGINEERING > ELECTRONICS
9) A continuous random variable X has uncountable many values in the interval [a, b]. If C is a value in the interval [a, b], then P(X = C)
A) is zeroB) is strictly non-zero
C) depends on the limits {a, b}D) is less than one, but non-zero
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Answer : is zero


ENGINEERING > ELECTRONICS
10) In the case of a random variable dealing with non-deterministic signals
A) it is a function from space of outcomes to the real/complex numbersB) it is a function with the probabilities of outcomes as random numbers
C) the values assumed by signals are always deterministicD) sometimes the events associated with random variable are deterministic
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Answer : it is a function from space of outcomes to the real/complex numbers