# Signals & Systems MCQ Questions & Answers

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

Question 1

Amplifiers, motors, filters etc. are examples for which type of system?

A. Distributed parameter systems
B. Unstable systems
C. Discrete time systems
D. Continuous time systems

Question 2

A system produces zero output for one input and same gives the same output for several other inputs. What is the system called?

A. Non – invertible System
B. Invertible system
C. Non – causal system
D. Causal system

Question 3

What are the tools used in a graphical method of finding convolution of discrete time signals?

A. Plotting, shifting, folding, multiplication, and addition in order
B. Scaling, shifting, multiplication, and addition in order
C. Scaling, multiplication and addition in order
D. Scaling, plotting, shifting, multiplication and addition in order

Question 4

An example of a discrete set of information/system is

A. the trajectory of the Sun
B. data on a CD
C. universe time scale
D. movement of water through a pipe

Question 5

Resistor performs amplitude scaling when x (t) is voltage, a is resistance and y (t) is output current.

A. True
B. False

Question 6

Comment on the causality of y[n] = x[-n].

A. Time invariant
B. Causal
C. Non causal
D. Time varying

Question 7

When we take up design of systems, ideally how do we define the stability of a system?

A. A system is stable, if a bounded input gives a bounded output, for some values of the input
B. A system is unstable, if a bounded input gives a bounded output, for all values of the input
C. A system is stable, if a bounded input gives a bounded output, for all values of the input
D. A system is unstable, if a bounded input gives a bounded output, for some values of the input

Question 8

A system is said to be defined as non causal, when

A. the output at the present depends on the input at an earlier time
B. the output at the present does not depend on the factor of time at all
C. the output at the present depends on the input at the current time
D. the output at the present depends on the input at a time instant in the future

Question 9

Is the system y(t) = Rx(t), where R is a arbitrary constant, a memoryless system?

A. Yes
B. No

Question 10

All causal systems must have the component of

A. memory
B. time invariance
C. stability
D. linearity

Question 11

Which of the component performs integration operation?

A. Resistor
B. Diode
C. Capacitor
D. Inductor

Question 12

What is the convolution of a signal with an impulse?

A. Signal itself
B. Impulse
C. A new signal
D. Signal multiplied by impulse

Question 13

AM radio signal is an example for __________

A. y (t) = a x (t)
B. y (t) = x1 (t) + x2 (t)
C. y (t) = x1 (t) * x2 (t)
D. y (t) = -x(t)

Question 14

Does the following discrete system have the parameter of memory, y[n] = x[n-1] + x[n] ?

A. Yes
B. No

Question 15

Which of the following is an example of physical device which adds the signals?

B. Audio mixer
C. Frequency divider
D. Subtractor

Question 16

Comment on the linearity of y[n] = n*x[n].

A. Linear
C. Not scalable
D. Non linear

Question 17

Should real time instruments like oscilloscopes be time invariant?

A. Yes
B. Sometimes
C. Never
D. They have no relation with time variance

Question 18

Construct the inverse system of y(t) = 2x(t)

A. y(t) = 0.5x(t)
B. y(t) = 2x(t)
C. y(2t) = x(t)
D. y(t) = x(2t)

Question 19

A time invariant system is a system whose output

A. increases with a delay in input
B. decreases with a delay in input
C. remains same with a delay in input
D. vanishes with a delay in input

Question 20

Time scaling is an operation performed on _______

A. Dependent variable
B. Independent variable
C. Both dependent and independent variable
D. Neither dependent nor independent variable

Question 21

y(t) = x(t-2) + x(2-t). Comment on its causality:

A. Causal
B. Time variant
C. Non causal
D. All of the above

Question 22

Y (t) = x (2t) is ________

A. Compressed signal
B. Expanded signal
C. Shifted signal
D. Amplitude scaled signal by a factor of 2

Question 23

y(t) = sin(x(t-1)) : Comment on its memory aspects.

A. Having memory
B. Needn’t have memory
C. Memoryless system
D. Time invariant system

Question 24

Comment on the causality of y[n] = n*x[n].

A. Time invariant
B. Time varying
C. Non causal
D. Causal

Question 25

Which of the passive component performs differentiation operation?

A. Resistor
B. Capacitor
C. Inductor
D. Amplifier

Question 26

In discrete signal, if y [n] = x [k*n] and k>1 then ______

A. Some samples are lost from x [n]
B. Some samples are added to x [n]
C. It has no effect on samples
D. Samples will be increased with factor k

Question 27

All real time systems concerned with the concept of causality are

A. non causal
B. causal
C. neither causal nor non causal
D. memoryless

Question 28

Y (t) = x (t/5) is _______

A. Compressed signal
B. Expanded signal
C. Time shifted signal
D. Amplitude scaled signal by factor 1/5

Question 29

What is the commutative property?

A. x(n)*h(n)=h(n)*x(n)
B. x(n)+h(n)=h(n)+x(n)
C. x(n)**h(n)=h(n)**x(n)
D. x(n)h(n)=h(n)x(n)

Question 30

Which of the following is an example of amplitude scaling?

A. Electronic amplifier
B. Electronic attenuator
C. Both amplifier and attenuator

Question 31

Which among the following systems are described by partial differential functions?

A. Causal Systems and Dynamic systems
B. Distributed parameter systems and linear systems
C. Distributed parameter systems and Dynamic systems
D. Causal systems and linear systems

Question 32

Is discrete time convolution possible?

A. True
B. False

Question 33

The type of systems which are characterized by input and the output quantized at certain levels are called as

A. analog
B. discrete
C. continuous
D. digital

Question 34

How is discrete time convolution represented?

A. x[n] + h[n]
B. x[n] – h[n]
C. x[n] * h[n]
D. x[n] + h[n]

Question 35

Choose the properties which are followed by a discrete time convolution?

A. Associative, commutative, distributive
B. Associative
C. Commutative and distributive
D. Distributive and associative

Question 36

y[t]= ∫x[t],t ranges from 0 to t. Is the system a memoryless one?

A. Yes
B. No
C. Both memoryless and having memory
D. None of the Mentioned

Question 37

What is the associative property of discrete time convolution?

A. [x1(n) * x2(n)]*h(n) = x1(n)* [x2(n)*h(n)]
B. [x1(n) * x2(n)]+h(n) = x1(n) + [x2(n)*h(n)]
C. [x1(n) + x2(n)]*h(n) = x1(n)* [x2(n)+h(n)]
D. [x1(n) * x2(n)]h(n) = x1(n) [x2(n)*h(n)]