250+ TOP MCQs on Elementary Signals – 2 and Answers

Signals & Systems Questions and Answers for Experienced people on “Elementary Signals – 2”.

1. Mathematical representation of given rectangular pulse is ______
A. X (t) = {2A, t/2 < 0 < -t/2
B. X (t) = {2A, -t/2 < 0 < t/2
C. X (t) = {2A, 0 <= |t| <= t/2
{0, |t| > t/2
D. X (t) = {2A, 0 <|t| < t/2
{0, |t| > t/2

Answer: C
Clarification: The given rectangular pulse is of amplitude 2A for the time interval –t/2 to t/2 and zero otherwise.

2. describe x [n] as superposition of two step functions.
A. X [n] = u [n] – u [n-5].
B. X [n] = u [n] + u [n-5].
C. X [n] = u [n-5] – u [n].
D. X [n] = u [n-5] + u [n].

Answer: A
Clarification: X [n] will be of amplitude for the interval 0 to 4 and zero otherwise. It can be obtained by the equation x [n] = u [n] – u [n-5].

3. Discrete-time version of unit impulse is defined as ______

Answer: A
Clarification: Unit impulse is an elementary signal with zero amplitude everywhere except at n = 0.

4. Which of the following is not true about unit impulse function?

Answer: D
Clarification: One option gives the definition of discrete-time version of impulse function, other options gives continuous-time representation of impulse function.

5. The step function u (t) is integral of _______ with respect to time t.
A. Ramp function
B. Impulse function
C. Sinusoidal function
D. Exponential function

Answer: B
Clarification: Step function is an integral of impulse function and conversely, impulse is the derivative of step function u (t).

6. The area under the pulse defines _____ of the impulse.
A. Strength
B. Energy
C. Power
D. Duration

Answer: A
Clarification: The area under the pulse defines strength of the impulse and the strength of the impulse is denoted by the label next to the arrow.

7. Unit impulse ∂(t) is _____ of time t.
A. Odd function
B. Even function
C. Neither even nor odd function
D. Odd function of even amplitude

Answer: B
Clarification: For an impulse function, ∂(-t)= ∂(t). Hence unit impulse is an even function of time t.

8. Shifting property of impulse ∂(t) is given by ______

Answer: A
Clarification: X (t) be a function and the product of x (t) with time shifted delta function ∂(t – to) gives x(to), this is referred to as shifting property of impulse function.

9. ∂(at) = ¹⁄_a ∂(t), this property of unit impulse is called ______
A. Time shifting property
B. Time scaling property
C. Amplitude scaling property
D. Time reversal property

Answer: B
Clarification: Impulse function exhibits shifting property, time scaling property. And time scaling property is given by∂(at) = ¹⁄_a ∂(t).

10. Which of the following is not true about the ramp function?
B. r (t) = t u (t)
C. Ramp function with unit slope is integral of unit step
D. Integral of unit step is a ramp function of unit slope

Answer: d
Clarification: The impulse function is derivative of the step function. In the same way the integral of step function is a ramp function of unit slope.
∫u(t) = r(t).