# Signals and systems MCQ Questions & Answers

Signals and systems MCQs : This section focuses on the "Signals and systems". These Multiple Choice Questions (MCQs) should be practiced to improve the Signals and systems skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

Which one is a linear system?

A. y[n] = x[n] x x[n - 1]
B. y[n] = x[n] + x[n - 10]
C. y[n] = x2[n]
D. (a) and (c)

Question 2

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

Question 3

If £[f(t)] = F(s), then £[f(t - T)] =

A. est F(s)
B. e-st F(s)

Question 4

The signal defined by the equations f(t) = 0 for t < 0, f(t) = E for 0 ≤ t ≤ a and f(t) = 0 for t > a is

A. a step function
B. a pulse function
C. a shifted step function originating at t = a
D. none of the above

Question 5

A signal g(t) = A then g(t) is a

A. energy signal
B. power signal
C. neither energy nor power signal
D. insufficient data

Question 6

Feedback path is present in-

A. Open system
B. Closed system
C. Both open and closed system
D. Neither present in open nor in closed systems

Question 7

Differentiation of ramp signal gives

A. Step signal
B. Impulse signal
C. 1
D. 0

Question 8

If f(t) = A d(t - a), F(s) is

A. A e-as
B. A eas
C. A a e-as
D. Aa eas

Question 9

As per time displacement theorem in Laplace transformation, displacement in the time domain by T becomes

A. division by s in the s domain
B. division by e-sT in the s domain
C. multiplication by s in the s domain
D. multiplication by e-sT in the s domain

Question 10

An impulse function consist of

A. pure dc
B. pure a.c
C. entire frequency range with constant phase
D. infinite bandwidth with linear phase vaariations

Question 11

A voltage V(t) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt2. If it is measured by a dc meter. The reading will be

A. 0
B. 4
C. 2
D. 2

Question 12

The analog signal given below is sampled by 600 samples per second for m(t) = 3 sin 500 pt + 2 sin 700 pt then folding frequency is

A. 500 Hz
B. 700 Hz
C. 300 Hz
D. 1400 Hz

Question 13

Two function g1(t) and g2(t) with correlation of 6 has average power of 4 and 5 respectively. The power of g1(t) + g2(t) is

A. 9
B. 21
C. 3
D. 15

Question 14

A first order system will never be able to give a __________ response band stopband passall pass Choose the correct option

A. 1, 2, 3 true
B. 1 and 3 true, 2 false
C. 1, 2 are true 3 is false
D. 1, 2 are false, 3 is true

Question 15

Z transform is a non-linear operation.

A. TRUE
B. FALSE

Question 16

Which one is a causal system?

A. y(n) = 3x[n] - 2x[n - 1]
B. y(n) = 3x[n] + 2x[n + 1]
C. y(n) = 3x[n + 1] + 2x[n - 1]
D. y(n) = 3x[n + 1] 2x[n - 1] + x[n]

Question 17

Double integration of a unit step function would lead to

A. an impulse
B. a parabola
C. a ramp
D. a doublet

Question 18

The analog signal m(t) is given below m(t) = 4 cos 100 pt + 8 sin 200 pt + cos 300 pt, the Nyquist sampling rate will be

A. 1/100
B. 1/200
C. 1/300
D. 1/600

Question 19

A signal m(t) is multiplied by a sinusoidal waveform of frequency fc such thatv(t)=m(t) cos 2pfctIf Fourier transform of m(t) is M(f), Fourier transform of v(t) will be

A. 0.5 M(f + fc)
B. 0.5 M(f - fc)
C. 0.5 M(f + fc) + 0.5 M(f - fc)
D. 0.5 M(f - fc) + 0.5 M(f - fc)

Question 20

A system where output depends on past and present inputs but not on future inputs is called-

A. Causal system
B. Non causal system
C. Stable system
D. Unstable system

Question 21

In an ac circuit the fundamental component of current wave lags the corresponding voltage wave by 20°. The third harmonic component of current wave lags the corresponding voltage by an angle.

A. less than 20°
B. more than 20°
C. equal to 20°
D. equal to or more than 20°

Question 22

In Laplace transform, multiplication by e-at in time domain becomes

A. translation by a in s domain
B. translation by (-a) in s domain
C. multiplication by e-as in s domain
D. none of the above

Question 23

An energy signal has G(f) = 10. Its energy density spectrum is

A. 10
B. 100
C. 50
D. 20

Question 24

A voltage wave having 5% fifth harmonic content is applied to a series RC circuit. The percentage fifth harmonic content in the current wave will be

A. 5%
B. more than 5%
C. less than 5%
D. equal or more than 5%

Question 25

δ(t) is a

A. energy signal
B. power signal
C. neither energy nor power
D. none

Question 26

The Fourier series of an odd periodic function contains

A. odd harmonics only
B. even harmonics only
C. cosine harmonics only
D. sine harmonics only

Question 27

Under which condition among the following, will x(t) be a periodic signal?

A. x(t)=x(t+nT), where T=time period and n=natural number.
B. x(t)=x(t+nT), where T=time period and n=whole number.
C. x(t)=x(t+nT), where T=time period and n=integer
D. x(t)=x(t+nT), where T=time period and n=any finite integer.

Question 28

If transfer function of a system is H(z) = 6 + z-1 + z-2 then system is

A. minimun phase
B. maximum phase
C. mixed phase
D. none