Explore topic-wise MCQs in Electronics & Communication Engineering.

This section includes 902 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.

51.

For a wave v = V 1m sin (ωt + θ1 ) - V3m sin (3ωt + θ3), the rms value is (0.5 V21m + 0.5 V23m)0.5

A. True
B. False
Answer» B. False
Discussion
52.

The function Ae(s + jω)t represens a rotating phasor having a magnitude increasing with time.

A. True
B. False
Answer» B. False
Discussion
53.

Assertion (A): In order that f(t) is Laplace transformable, it is necessary that for real positive σ1 Reason (R): If f(t) is known we can find F(s) and vice versa.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» C. A is true, R is false
Discussion
54.

Assertion (A): The function kest with both σ and ω positive and s > 0 depicts a sinusoid whose amplitude increases with time. Reason (R): If σ = 0, kest becomes a sinusoid.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» C. A is true, R is false
Discussion
55.

Assertion (A): In complex frequency s = σ + jω, the terms s and ω are nepar frequency and radin frequency. Reason (R): If ω = 0, the graph of Kest will be a decaying exponential if s

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» C. A is true, R is false
Discussion
56.

Assertion (A): The exponential form of Fourierseries is Reason (R): If f(t) is an even function, the coefficients Fn are real.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» C. A is true, R is false
Discussion
57.

Assertion (A): The Fourier series of the wave shown in the figure does not contain even harmaonics Reason (R): If f(t) = - f(t ± T/2) the function is said to have half wave symmetry.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» C. A is true, R is false
Discussion
58.

Assertion (A): If a wave v = A1 + A2 sin ωt is applied to a pure capacitor the current wave isi = A3 sin(ωt + 90°) Reason (R): A capacitor presents infinite impedance to dc.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» B. Both A and R are correct but R is not correct explanation of A
Discussion
59.

Assertion (A): The rms value of v = 1 + sin ωt is 1.5Reason (R): If i = I0 + I1m sin ω1t + I3m sin 3ω1t, then

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true
Answer» B. Both A and R are correct but R is not correct explanation of A
Discussion
60.

Algebraic expression for z-transform of x[n] is X[z]... What is the algebraic expression of z-transform of ejω0n x[n]?

A. X(Z - Z0)
B. X(e-jW0z)
C. X(ejω0z)
D. X(Z)jω0z
Answer» C. X(ejω0z)
Discussion
61.

Average power for signal is

A. 0
B. ∞
C. 1
D. [D].
Answer» E.
Discussion
62.

The signal x(t) = A cos (ω0t + φ) is

A. energy signal
B. power signal
C. energy Power
D. none
Answer» C. energy Power
Discussion
63.

The F.T. of e-pf2 is e-pf2 then Fourier Transform of e -at2 is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
64.

The F.T. X(f) of the periodic delta functions.

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
65.

The range of values of a and b for which the linear time invariant system with impulse response. h(n) = an n ≥ 0         = bn n < 0 will be stable if

A. |a| > 1, |b| > 1
B. |a| < 1, |b| < 1
C. |a| < 1, |b| > 1
D. |a| > 1, |b| < 1
Answer» D. |a| > 1, |b| < 1
Discussion
66.

Given, Lf(t) = F(s) &Rightarrow; which of the following expression are correct? L[f(t - a) ∪ (t - a)] = F(s)e-saL(t - a)f(t) = as F(s) Select the correct answer using the codes given below

A. 1, 2, 3
B. 1, 2, 4
C. 2, 3, 4
D. 1, 3, 4
Answer» C. 2, 3, 4
Discussion
67.

The inverse response of a system h(n) = an∪(n) what is the condition for the system to be BIBO stable?

A. a is real and +ve
B. a is real and -ve
C. |a| > 1
D. |a| < 1
Answer» D. |a| < 1
Discussion
68.

which is the Laplace transform of x(t) = -e2t ∪(t) ⊕ t ∪(t)?

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
69.

The unit step response of a system starting from rest is given by c(t) = 1 - e-2t for t ≥ 0. The transfer function of the syste is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
70.

If the region of convergence of x1(n) + x2(n) is then the region of convergence of x1[n] - x2[n] includes

A. [A].
B. [B].
C. [C].
D. [D].
Answer» E.
Discussion
71.

A signal x(n) = sin(ω0n + φ) is the input to a linear time invariant system having a frequency response H(ejω) If the O/P of the system is Ax(n -n0), then the general form of H(ejω) will be

A. - n0ω0 + β for any arbitrary real β
B. - n0ω0 + 2pk for any arbitrary integer k
C. n0ω0 + 2pk for any arbitrary integer k
D. - n0ω0 + φ
Answer» C. n0ω0 + 2pk for any arbitrary integer k
Discussion
72.

The output y(t) of a linear time invariant system is related to its input x(t) by the following equation y(t) = 0.5x(t - td + 1) + x(t - td) + 0.5 x(t - td + 7). The filter transfer function H(ω) of such a system is given by

A. (1 + cos ωt)e-jωt d
B. (1 + 0.5 cos ωt)e-jωt d
C. (1 + cos ωt)ejωt d
D. (1 - 0.5 cos ωt)e-jωt d
Answer» B. (1 + 0.5 cos ωt)e-jωt d
Discussion
73.

The region of converage of z-transform of sequence must be

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
74.

A casual system having the transfer function is excited with 10 ∪(t). The time at which the output reaches 99% of its steady-state value is

A. 2.7 sec
B. 2.5 sec
C. 2.3 sec
D. 2.1 sec
Answer» D. 2.1 sec
Discussion
75.

A casual LTI system is described by the difference equation 2y[n] = ay[n - 2] - 2x[n] + βx[n -1] The system is stable only if

A. |a| = 2 |β| < 2
B. |a| > 2 |β| > 2
C. |a| < 2 any value of β
D. |β| < 2, any value of a
Answer» D. |β| < 2, any value of a
Discussion
76.

ROC of sequence x[n] = (3)n ∪[n] + (4)n ∪[- n - 1]

A. |z| > 4
B. 3 < |z| < 4
C. |z| < 4
D. |z| > 3
Answer» C. |z| < 4
Discussion
77.

The ROC of sequence x[n] = (0.8)n ∪[n] + (0.4)n ∪[n]

A. |z| > 0.8
B. |z| > 0.4
C. 0.4 < |z| < 0.8
D. |z| < 0.8
Answer» B. |z| > 0.4
Discussion
78.

The ROC of sequence in the Z.T. of sequence x[n] = an ∪ [n] is

A. z > a
B. z < a
C. |z| > a
D. |z| < a
Answer» D. |z| < a
Discussion
79.

The Z.T. of sequence x[n] = an ∪ [n] is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
80.

The impulse response of discrete time system is x[n] = (4)n ∪[3 - n], the system is

A. casual
B. stable
C. stable and casual
D. stable and non-casual
Answer» E.
Discussion
81.

The impulse response of the DT - LTI system is given below       Check whether the system is StableCasualDynamic.

A. 1 and 2
B. 2 and 3
C. 1 and 3
D. 1, 2 and 3
Answer» E.
Discussion
82.

The range of value "a" for which system will be stable. If impulse response of DT system is = an ∪[n]

A. a > 1
B. a < 1
C. 1 < a < ∞
D. -1 < a < 1
Answer» E.
Discussion
83.

Energy density spectrum of x[n] = an∪[n] for -1 < a < + 1 is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
84.

DTFT (Discrete time Fourier transform) of x[n] = an∪[n] for -1 < a < + 1.

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
85.

what will be sampling rate to aviod aliasing for the signal m(t) = 10 cos 100 pt?

A. ≤ 100 n2
B. ≥ 100 n2
C. [C].
D. [D].
Answer» E.
Discussion
86.

The joint probability function of two discrete random variable X and Y is given by x = 0, 2, y = 2, 3 then E(y) is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
87.

The joint probability function of two discrete random variable X and Y is given by x = 0, 2, y = 2, 3 variance σ2 will be[Hint: σ2 = E(X2) - μ2 &Rightarrow; E(X2) - (E(X))2]

A. [A].
B. [B].
C. [C].
D. zero
Answer» C. [C].
Discussion
88.

If otherwise find E(X)

A. [A].
B. [B].
C. [C].
D. 0
Answer» B. [B].
Discussion
89.

The joint probability function of two discrete random variable X and Y is given by x = 0, 2, y = 2, 3 then E(X) =

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
90.

A linear system is characterized by H(ω) = Be-2ω2 the system is physically

A. unrealizable
B. realizable
C. depends upon B
D. depends upon constant 2
Answer» B. realizable
Discussion
91.

Transfer function of a linear system is 200 e-j10ω The system is a

A. distortionless Attenuator
B. amplifier with Phase distortion
C. distortionless Amplifier
D. attenuator with Phase distortion
Answer» D. attenuator with Phase distortion
Discussion
92.

δ(t) dt is a

A. Unit step
B. 0
C. r(t)
D. sinc
Answer» B. 0
Discussion
93.

The sampling of a function f(l) = sin 2pf0t starts from a zero crossing. The signal can be detected if sampling time T is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
94.

The value of Integral (t2 + 2) δ(t - 3)dt is equal to

A. 11
B. 3
C. 9
D. 0
Answer» E.
Discussion
95.

The value of Integral δ(t) sin t dt is equal to

A. zero
B. 1
C. infinite
D. undefined
Answer» B. 1
Discussion
96.

X and Y are two random variable and Z = X + Y. Let σx2, σy2 and σz2 be variance of X, Y and Z. Then

A. σz2 = σx2 + σy2
B. σz2 ≤ σx2 + σy2
C. σz2 < σx2 + σy2
D. σz2 > σx2 + σy2
Answer» B. σz2 ≤ σx2 + σy2
Discussion
97.

consider the following as regards cumulative disribution function F(x)0 ≤ F(x) ≤ 1F(- ∞) = 0F(∞) = 1F(x1) ≤ F(x2) If x1 < x2 Out of above which are correct?

A. 1 and 2 only
B. 1, 2 and 3 only
C. 1, 2, 3 and 4
D. 2 and 4
Answer» D. 2 and 4
Discussion
98.

An experiment is repeated N times. One event A occurs NA times. Then

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
99.

The enery E associated with time function f(t) is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
100.

If f(k) ↔ F(z), then kn fk ↔

A. [F(z)]n
B. [B].
C. [F(z)]1/n
D. [D].
Answer» E.
Discussion