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

Question 1

The characteristic equation of a closed-loop control system is given by s³ + 6s² + 11s + K = 0. For the system to be stable, which of the following conditions must be met for the gain K?

Accepted Answer

0 < K < 66

Answer

K > 66

Answer

K < 0

Answer

K > 0

Question 2

An engineer is analyzing a system's frequency response using a Bode magnitude plot. In a specific frequency range, the plot shows a consistent downward slope of -40 dB/decade. What does this slope most likely indicate about the system's transfer function in that range?

Accepted Answer

Two poles or a double pole

Answer

A single pole

Answer

A single zero

Answer

Two zeros or a double zero

Question 3

A control systems engineer observes that a process under proportional-integral (PI) control exhibits a persistent steady-state error after a step change in the setpoint. Which of the following is the most likely cause?

Accepted Answer

The integral time (Ti) is too large, resulting in weak integral action.

Answer

The proportional gain (Kp) is too high.

Answer

The derivative gain (Kd) is set to zero.

Answer

The system has entered integral windup.

Question 4

In the context of a system's transfer function in the s-plane, what is the primary significance of a pole's location?

Accepted Answer

It dictates the system's stability and transient response characteristics.

Answer

It determines the initial value of the system's step response.

Answer

It defines the frequencies at which the system's output is completely attenuated.

Answer

It specifies the steady-state error of the system to a ramp input.

Question 5

A continuous-time signal is band-limited to a maximum frequency of 4 kHz. According to the Nyquist-Shannon sampling theorem, what is the minimum sampling rate required to avoid aliasing and allow for perfect reconstruction of the signal?

Accepted Answer

8 kHz

Answer

4 kHz

Answer

2 kHz

Answer

16 kHz

Question 6

Which of the following input-output relationships, y(t), describes a system that is linear but NOT time-invariant?

Accepted Answer

y(t) = x(t) * cos(2πt)

Answer

y(t) = x(t-2)

Answer

y(t) = x²(t)

Answer

y(t) = x(t) + 5

The characteristic equation of a closed-loop control system is given by s³ + 6s² + 11s + K = 0.For the system to be stable, which of the following conditions must be met for the gain K?

The characteristic equation of a closed-loop control system is given by s³ + 6s² + 11s + K = 0.
For the system to be stable, which of the following conditions must be met for the gain K?