# Introduction to Signals and Systems - MCQs with answers

## Introduction to Signals and Systems - MCQs with answers

1. Which mathematical notation specifies the condition of periodicity for a continuous time signal ?

a. x(t) = x( t +T0)

b. x(n) = x( n+ N)

c. x(t) = e-αt

d. None of the above

ANSWER: a. x(t) = x( t +T0)

2. Which property of delta function indicates the equality between the area under the product of function with shifted impulse and the value of function located at unit impulse instant ?

a. Replication
b. Sampling
c. Scaling
d. Product

3. Which among the below specified conditions/cases of discrete time in terms of real constant 'a' , represents the double-sided decaying exponential signal?

a. a > 1
b. 0 < a < 1
c. a < -1
d. -1 < a < 0

ANSWER: d. -1 < a < 0

4. Damped sinusoids are _____

a. sinusoid signals multiplied by growing exponentials

b. sinusoid signals divided by growing exponentials

c. sinusoid signals multiplied by decaying exponentials

d. sinusoid signals divided by decaying exponentials

ANSWER: c. sinusoid signals multiplied by decaying exponentials

5. An amplitude of sinc function that passes through zero at multiple values of an independent variable 'x' ______

a. decreases with an increase in the magnitude of an independent variable (x)

b. increases with an increase in the magnitude of an independent variable (x)

c. always remains constant irrespective of variation in magnitude of' x'

d. cannot be defined

ANSWER: a. decreases with an increase in the magnitude of an independent variable (x)

6. A system is said to be shift invariant only if______

a. a shift in the input signal also results in the corresponding shift in the output

b. a shift in the input signal does not exhibit the corresponding shift in the output

c. a shifting level does not vary in an input as well as output

d. a shifting at input does not affect the output

ANSWER: a. a shift in the input signal also results in the corresponding shift in the output

7. Which condition determines the causality of the LTI system in terms of its impulse response ?

a. Only if the value of an impulse response is zero for all negative values of time

b. Only if the value of an impulse response is unity for all negative values of time

c. Only if the value of an impulse response is infinity for all negative values of time

d. Only if the value of an impulse response is negative for all negative values of time

ANSWER: a. Only if the value of an impulse response is zero for all negative values of time

8. Under which conditions does an initially relaxed system become unstable ?

a. only if bounded input generates unbounded output
b. only if bounded input generates bounded output
c. only if unbounded input generates unbounded output
d. only if unbounded input generates bounded output

ANSWER: a. only if bounded input generates unbounded output

9. Which among the following are the stable discrete time systems?

1. y(n) = x(4n)
2. y(n) = x(-n)
3. y(n) = ax (n) + 8
4. y(n) = cos x(n)

a. 1 & 3
b. 2 & 4
c. 1, 3 & 4
d. 1,2,3 & 4

10. An equalizer used to compensate the distortion in the communication system by faithful recovery of an original signal is nothing but an illustration of _________

a. static system
b. dynamic system
c. invertible system
d. none of the above