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.

101.

If f(t) ↔ F(jω), ↔

A. F(jω)
B. [F(jω)]n
C. (jω)n F(jω)
D. [D].
Answer» D. [D].
Discussion
102.

eAt can be expanded as

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
103.

If then, f(0+) and f(∞) are given by

A. 0 and 2
B. 2, 0
C. 0, 1
D. , 0
Answer» C. 0, 1
Discussion
104.

A probability density function is given by p(x) = Ke-x2/2 for -∞ < x < ∞ , The value of K should be

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
105.

Laplace transform of eat cos (at) is

A. [A].
B. [B].
C. [C].
D. none of these
Answer» B. [B].
Discussion
106.

Give that is

A. [A].
B. [B].
C. [C].
D. None of these
Answer» C. [C].
Discussion
107.

The z transform of fk = ak is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
108.

If and A + B is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
109.

The Fourier series representation of a periodic current (2 + 62 cos ωt +48 sin 2ωt) A. The effective value is

A. (2 + 6 + 24) A
B. 8 A
C. 6 A
D. 2 A
Answer» C. 6 A
Discussion
110.

Consider the following sets of values of E, R and C for the circuit in the given figure. 2 V, 1 Ω, 1.25 F1.6 V, 0.8 Ω, 1 F1.6 V, 1 Ω, 0.8 F2 V, 1.25 Ω, 1 F Which of these of values will ensure that the state equation is valid?

A. 1 and 4
B. 1 and 2
C. 3 and 4
D. 2 and 3
Answer» E.
Discussion
111.

Fourier transform of e-a|t| is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
112.

If v(t) = 0 for t < 0 and v(t) = e -at for t ≥ 0, V(jω) =

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
113.

Given that h(t) = 10e-10t u(t) and e(t) = sin 10t u(t). The Laplace transform of f(t) = h(t - t) e(t)dt is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
114.

If x(t) and its first derivative are Laplace transformable and Laplace of transform x(t) is X(s), then x(t) is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
115.

If δ(t) denotes a unit impulse, Laplace transform of is

A. 1
B. s2
C. s
D. s-2
Answer» C. s
Discussion
116.

The Fourier transform of f(t) = cos ω0t is

A. p[δω0 + δ(- ω0)]
B. p[δ(ω - ω0) + δ(ω + ω0)]
C. p[δω0 - δ(- ω0)]
D. p[δ(ω - ω0) - δ(ω + ω0)]
Answer» C. p[δω0 - δ(- ω0)]
Discussion
117.

Fourier transform of the unit step function (i.e., u(t) = 1 for t ≥ 0 and u(t) = 0 for t < 0) is

A. pδ (ω)
B. [B].
C. [C].
D. [D].
Answer» D. [D].
Discussion
118.

In Laplace transforms s = σ + jω. Which of the following represents true natue of s. Select your answer using the given codes σ has a damping effectσ is responsible for convergence of integral f(t)e-st dtσ has a value less than zero Codes:

A. 1, 2 and 3
B. 1 and 2
C. 2 and 3
D. 1 and 3
Answer» C. 2 and 3
Discussion
119.

For the signal in the given figure the Fourier transform is Then the Fourier transform of the signal in the given figure

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
120.

The inverse Fourier transform of the function F(ω) = is

A. sin ωt
B. cos ωt
C. sgnt
D. u(t)
Answer» D. u(t)
Discussion
121.

As per mormal distribution the probability of an error between limits a and b is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
122.

The energy associated with a function f(t) is. In terms of Fourier transform, E =

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
123.

If the poles of H(z) are at

A. [A].
B. z = 1 and z = 3
C. [C].
D. z = -1 and z = -3
Answer» B. z = 1 and z = 3
Discussion
124.

Z transform of [(Xk±k0)] =

A. z±k0 X(z)
B. z±k0 X(z)
C. [C].
D. none of the above
Answer» B. z±k0 X(z)
Discussion
125.

If for k ≥ 0 and xk = 0 for k < 0, z transform of the sequence x is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
126.

If xk = 2k for k ≤ 0 and xk = 0 for k ≥ 0, Z transform of the sequence x is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» E.
Discussion
127.

If xk = 0 for k < 0 and xk = 2k for k 3 0, X(z) i.e., Z transform of sequence x is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
128.

A voltage v = 5 + 50 sin ωt/ + 5 sin 5 ωt is applied to a pure capacitor of capacitance 1 ωF. If f/= 314 rad/sec, current is

A. 1 + 0.0157 cos 314 t + 0.00785 cos 1570 t
B. 0.0157 cos 314 t + 0.00785 cos 1570 t
C. 0.0157 sin 314 t + 0.00785 sin 1570 t
D. 0.0157 sin (314 t / + 45°) + 0.00785 sin (1570 t + 45°)
Answer» C. 0.0157 sin 314 t + 0.00785 sin 1570 t
Discussion
129.

If ξ f(t) = F(jω), ξf(t-a) =

A. F(jω) e-jωa
B. F(jω) ejωa
C. [C].
D. a F(jω) ejωa
Answer» B. F(jω) ejωa
Discussion
130.

For the wave i = I0 + I1m sin ωt + I3m sin 3ωt, the rms value is

A. I = (I20 + I21m + I23m)0.5
B. [B].
C. I = 0.707 (I20 + I21m + I23m)0.5
D. none of these
Answer» C. I = 0.707 (I20 + I21m + I23m)0.5
Discussion
131.

The function A est where s = s + jω represents

A. A phasor whose magnitude changes with time
B. A phasor whose frequency is ω
C. A phasor rotating in counterclockwise direction at angular frequency ω and whose magnitude increases with t
D. A phasor rotating in clockwise direction at angular frequency ω and whose magnitude increases with t
Answer» D. A phasor rotating in clockwise direction at angular frequency ω and whose magnitude increases with t
Discussion
132.

The Laplace transform of sin ∝t is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
133.

For the function f(t) = e-at, the Laplace transform is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» E.
Discussion
134.

A discrete-time signal is given as\(x\left[ n \right] = \cos \frac{{\pi n}}{9} + \sin \left[ {\frac{{\pi n}}{7} + \frac{1}{2}} \right]\)The period N for the periodic signal is

A. 126
B. 32
C. 252
D. 64
Answer» B. 32
Discussion
135.

Consider impulse responseh(t) = -sin t ; -π < t < π, the system is:

A. unstable, causal
B. stable, causal
C. stable, non-causal
D. unstable, non-causal
Answer» D. unstable, non-causal
Discussion
136.

If the input x(t) and output y(t) of a system are related as y(t) = max (0, x(t)), then the system is

A. linear and time-invariant
B. linear and time-variant
C. non-linear and time-variant
D. non-linear and time-invariant
Answer» E.
Discussion
137.

In which system does the output at present instant depends on past inputs and outputs?

A. Invertible systems
B. Dynamic systems
C. Static systems
D. Linear systems
Answer» C. Static systems
Discussion
138.

Find the first derivative of the signal. X(t) = t[u(t) – u(t – a)], a > 0

A. u(t) + u(t – a) – aδ(t –a)
B. u(t) – δ(t – a)- aδ(t – a)
C. u(t) – u(t – a) + aδ(t – a)
D. u(t) – u(t – a) –aδ(t – a)
Answer» E.
Discussion
139.

\(\mathop \smallint \nolimits_{ - 7}^2 \left( {{t^2} + {t^3} + 1} \right)\delta \left( {t - 3} \right)dt = \_\_\_\_\)

A. 3
B. 37
C. 13
D. 0
Answer» E.
Discussion
140.

Consider an ideal low pass filter. Such a discrete-time system is:

A. always realizable physically
B. never realizable physically
C. a non-linear system
D. a linear, causal system
Answer» C. a non-linear system
Discussion
141.

A unit step function on integration results in a:

A. Unit doublet
B. Unit step function
C. Unit parabolic function
D. Unit ramp function
Answer» E.
Discussion
142.

An input signal \(\rm x(t) = 2 + 5 \sin{(100πt)}\) is sampled with a sampling frequency of \(\rm 400\ Hz\) and applied to the system whose transfer function is represented by\(\rm \frac{{Y\left( z \right)}}{{X\left( z \right)}} = \frac{1}{N}\left( {\frac{{1 - {z^{ - N}}}}{{1 - {z^{ - 1}}}}} \right)\)where, \(\rm N\) represents the number of samples per cycle. The output \(\rm y[n]\) of the system under steady state is

A. \(\rm 0\)
B. \(\rm 1\)
C. \(\rm 2\)
D. \(\rm 5\)
Answer» D. \(\rm 5\)
Discussion
143.

Determine whether the following signals are energy signals, power signals, or neither.(a) x(t) = e-at u(t), a > 0(b) x[n] = 2ej3n

A. (a) is power signal (b) is energy signal
B. (a) and (b) are power signals
C. (a) is energy signal (b) is power signal
D. (a) and (b) are energy signals
Answer» D. (a) and (b) are energy signals
Discussion
144.

In analog communication, a unit impulse response of a causal system is ______ for t < 0.

A. 0
B. 1
C. infinite
D. -1
Answer» B. 1
Discussion
145.

Identify the correct condition for an even signal.

A. X(t) = X(n)
B. X(t) = –X(–t)
C. X(t) = X(–t)
D. X(t) = X(t + n)
Answer» D. X(t) = X(t + n)
Discussion
146.

Consider the following statements with respect to the bilinear transformation method of digital filter design:1. It preserves the number of poles and thereby the order of the filter.2. It maintains the phase response of the analog filter.3. The impulse response of the analog filter is not preserved.Which of the above statements are correct?

A. 1, 2 and 3
B. 1 and 2 only
C. 1 and 3 only
D. 2 and 3 only
Answer» D. 2 and 3 only
Discussion
147.

Consider an impulse response h[n] = {-3, -1, 2, 1, 3}, system is ______ phase and ______ pass filter.

A. Linear, low
B. Linear, high
C. Linear, band
D. Non-linear, band
Answer» E.
Discussion
148.

For a periodic signal v(t) = 30 sin 100t + 10 cos 300t + 6sin (500t + π\4), the fundamental frequency in rad/s

A. 100
B. 300
C. 500
D. 1500
Answer» B. 300
Discussion
149.

Consider a cascade system with unit step u(t) as input and h1(t) = e-2t(t)u(t) and h2(t) = e-t(t)u(t) respectively. The impulse response of overall system is:

A. h(t) = x2(t) e-tu(t)
B. h(t) = [e-t – e-2t]u(t)
C. h(t) = t2 e-2t u(t)
D. h(t) = 2t2 e-2t u(t)
Answer» C. h(t) = t2 e-2t u(t)
Discussion
150.

Consider the signal x(t) = 10 cos (10πt + π/7) + 4 sin (30πt + π/8). Its power lying within the frequency band 10 Hz to 20 Hz is

A. 4 W
B. 8 W
C. 50 W
D. 58 W
Answer» C. 50 W
Discussion