BEE FREE BEE Bachelor of Electrical Engineering Signals and Control Systems Questions and Answers 2

Question 1

What is the Laplace transform of a unit ramp function r(t) = t·u(t)?

Accepted Answer

1/s²

Answer

The Laplace transform of t·u(t) is 1/s².

Question 2

A system with transfer function G(s) = 5/(s² + 4s + 5) has poles at which locations?

Accepted Answer

-2 ± j

Answer

Using the quadratic formula on s² + 4s + 5 = 0 gives s = -2 ± j1.

Question 3

In a Bode plot, a first-order pole contributes what slope change at its corner frequency?

Accepted Answer

-20 dB/decade

Answer

A single real pole introduces a -20 dB/decade asymptotic slope change at the break frequency.

Question 4

What does the Nyquist stability criterion use to determine closed-loop stability?

Accepted Answer

Number of encirclements of the -1 point

Answer

The Nyquist criterion counts encirclements of the critical point -1+j0 by the open-loop frequency response.

Question 5

For a continuous-time LTI system, if the impulse response h(t) is absolutely integrable, the system is considered:

Accepted Answer

BIBO stable

Answer

Absolute integrability of the impulse response is the necessary and sufficient condition for BIBO stability.

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