# Useful Signals MCQ’s

This set of Signals & Systems Multiple Choice Questions & Answers (MCQs) focuses on “Useful Signals”.

1. What is the value of u, where u[n] is the unit step function?
a) 1
b) 0.5
c) 0
d) -1

2. Evaluate the following function in terms of t: {sum from -1 to infinity:d[n]}/{Integral from 0 to t: u(t)}
a) t
b) 1t
c) t2
d) 1t2

3. What is the value of d, such that d[n] is the unit impulse function?
a) 0
b) 0.5
c) 1.5
d) 1

4. Evaluate the following function in terms of t: {integral from 0 to t}{Integral from -inf to inf}d(t)
a) 1t
b) 1t2
c) t
d) t2

5. Find the magnitude of exp(jwt). Find the boundness of sin(t) and cos(t).
a) 1, [-1,2], [-1,2]
b) 0.5, [-1,1], [-1,1]
c) 1, [-1,1], [-1,2]
d) 1, [-1,1], [-1,1]

6. Compute d[n]d[n-1] + d[n-1]d[n-2] for n = 0, 1, 2.
a) 0, 1, 2
b) 0, 0, 1
c) 1, 0, 0
d) 0, 0, 0

7. The fundamental period of exp(jwt) is
a) pi/w
b) 2pi/w
c) 3pi/w
d) 4pi/w

8. Find the value of {sum from -inf to inf} exp(jwn)*d[n].
a) 0
b) 1
c) 2
d) 3

9. Defining u(t), r(t) and s(t) in their standard ways, are their derivatives defined at t = 0?
a) Yes, Yes, No
b) No, Yes, No
c) No, No, Yes
d) No, No, No

10. The range for unit step function for u(t – a), is ________
a) t < a
b) t ≤ a
c) t = a
d) t ≥ a

11. Which one of the following is not a unit step function?

a)

b)

c)

d)

12. Evaluate:
a) {2,1.5,0,6}
b) {2,1.5,6,0}
c) {2,0,1.5,6}
d) {2,1.5,0,3}

13. Which is the correct Euler expression?
a) exp(2jt) = cos(2t) + jsin(t)
b) exp(2jt) = cos(2t) + jsin(2t)
c) exp(2jt) = cos(2t) + sin(t)
d) exp(2jt) = jcos(2t) + jsin(t)

14. Which one of the following is not a ramp function?
a) r(t) = t when t ≥ 0
b) r(t) = 0 when t < 0
c) r(t) = ∫u(t)dt when t < 0
d) r(t) = du(t)dt

15. Unit Impulse function is obtained by using the limiting process on which among the following functions?
a) Triangular Function
b) Rectangular Function
c) Signum Function
d) Sinc Function

16. When is a complex exponential signal pure DC?
a) σ = 0 and Ω < 0
b) σ < 0 and Ω = 0
c) σ = 0 and Ω = 0
d) σ < 0 and Ω < 0 5 Star
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