This set of Signals & Systems Questions and Answers for Experienced people focuses 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

View Answer

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

2. If 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].

View Answer

Explanation: 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 ______

View Answer

Explanation: 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?

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: 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

View Answer

Explanation: 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 ______

View Answer

Explanation: 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

View Answer

Explanation: 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?

a)

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

View Answer

Explanation: 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).

**Sanfoundry Global Education & Learning Series – Signals & Systems.**

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