# 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

Differentiation of ramp signal gives

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

Question 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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

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

Question 11

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 12

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 13

Double integration of a unit step function would lead to

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

Question 14

δ(t) is a

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

Question 15

If £[f(t)] = F(s), then £[f(t - T)] =

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

Question 16

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 17

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

Question 18

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 19

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 20

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 21

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 22

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 23

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 24

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 25

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 26

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 27

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 28

Which one most appropriate dynamic system?

A. y(n) + y(n - 1) + y(n + 1)
B. y(n) + y(n - 1)
C. y(n) = x(n)
D. y(n) + y(n - 1) + y(n + 3) = 0