Signals and Systems MCQs | Signals and Systems Multiple Choice Questions and Answers

Questions
1 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

Answer: discrete
2 The type of systems which are characterized by input and the output capable of taking any value in a particular set of values are called as
A Analog
B Discrete
C Digital
D Continuous

Answer: Continuous
3 Should real time instruments like oscilloscopes be time invariant?
A Yes
B Sometimes
C Never
D They have no relation with time variance

Answer: Yes
4 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

Answer: the output at the present depends on the input at a time instant in the future
5 What is the other name of a Continuous Time Unit Impulse Function?
A Dirac delta function
B Unit function
C Area function
D Direct delta function

Answer: Dirac delta function
6 Why is the impulse duration important?
A It is zero
B It changes with time
C It approaches zero
D It depends on the situation

Answer: It approaches zero
7 What is a doublet function?
A Branch of an impulse function
B The output of an impulse function
C The first derivative of an impulse function
D Any continuous time impulse function has another name that is doublet function

Answer: The first derivative of an impulse function
8 How are discrete unit impulse functions and discrete time unit step functions related?
A They are inverse of each other
B ∂(n)=u(n)-u(n-1)
C ∂(n)=u(n)*2∂
D Integration of unit step function gives unit step function

Answer: ∂(n)=u(n)-u(n-1)
9 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

Answer: Sampling
10 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: sinusoid signals multiplied by decaying exponentials
11 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 shift in the input signal also results in the corresponding shift in the output
12 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

Answer: 1,2,3 & 4
13 If a function f(t) u(t) is shifted to right side by t0,then the function can be expressed as
A f(t – t0) u(t)
B f(t) u(t – t0)
C f(t – t0) u(t – t0)
D f(t +t0) u(t + t0)

Answer: f(t – t0) u(t – t0)
14 Which block of the discrete time systems requires memory in order to store the previous input?
A Signal Multiplier
B Unit Delay
C Adder
D None of the above

Answer: Unit Delay
15 The covariance function of a band limited white noise is
A A Dirac delta function
B An exponentially decreasing function
C A sinc function
D A sinc2 function

Answer: A sinc function
16 A discrete LTI system is non-causal if its impulse response is
A anu(n -2)
B an-2u(n)
C an+2u(n)
D anu(n +2)

Answer: anu(n +2)
17 What does the signalling rate in the digital communication system imply?
A Number of digital pulses transmitted per second
B Number of digital pulses transmitted per minute
C Number of digital pulses received per second
D Number of digital pulses received per minute

Answer: Number of digital pulses transmitted per second
18 What does the transfer function of a system describe for the system ?
A Only zero-input response
B Only zero-state response
C Both zero-input and zero-state response
D Neither zero-input response nor zero-state response

Answer: Only zero-state response
19 Which one of the following is the correct statement ? The system characterized by the equation y(t) = ax(t) + b is
A linear for any value of b
B linear if b > 0
C linear if b < 0
D non-linear

Answer: non-linear
20 Which one of the following systems described by the following input-output relations is non-linear ?
A y(n) = n x(2n)
B y(n) = x (n2)
C y(n) = n2x(n)
D y(n) = x2(n)

Answer: y(n) = x2(n)
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