Control System 10

Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Control System 10

Part 4: List for questions and answers of Control System II


Q1. The lag compensator

a) Increases the damping ratio

b) Decreases the damping ratio

c) Increases the band width

d) Increases the stability


Q2. Negative feedback in a closed loop control system

a) Reduce gain

b) Improves disturbance rejection

c) Reduce sensitivity to parameter variation

d) All of the above


Q3. The characteristic equation for closed loop system is given as s³ + 2s² + 4s + k = 0. The value of k for which the system becomes just stable is

a) 2

b) 4

c) 6

d) 8


Q4. The open loop transfer function of a unity feedback control system is G(s) = 1/((s(s+0.1s)(s+1)). The value of damping factor for which the resonant peek is equal to 1.4 is

a) 0.386

b) 0.263

c) 0.953

d) 0.707


Q5. The open loop transfer function of non unity negative feedback system is G(s) = ks/((s+1)(s+2)), then the number of root locus branches equal to

a) 1

b) 2

c) 3

d) 0 


Q6. A transfer function is given as G(s) = (s²+9)(s+2)/(s+4)(s+3)(s+9) The steady state sinusoidal response will become zero at a frequency response is

a) 2/ rad/s

b) 4 rad/s

c) 3 rad/s

d) 9 rad/s


Q7. In frequency response analysis of second order system, the error at corner frequency is

a) 20 log 

b) 10 log 

c) -20 log 

d) -10 logξ 


Q8. For a second order under damped system subjected to unit step input the time response has first peak value to be 4 times the second over shoot. Determine the damping ratio ? ?

a) 0.087

b) 0.87

c) 0.707

d) 0.07


Q9. Find the bandwidth of the system, when rise time of the system is give as 1msec?

a) 1 kHz

b) 500 Hz

c) 350 Hz

d) 750 Hz


Q10. If the bandwidth of the system is very large, the system response is

a) Faster

b) Slower

c) Independent of bandwidth

d) None of the above


Q11. The magnitude of a transfer function G(jω )H(jω ) at gain cross over frequency is

a) 0

b) 1

c) Infinity

d) Any of the above 


Q12. Find the conditions for the system to be stable?

a) Gain margin and phase margins are positive

b) Gain margin and phase margins are negative

c) Gain margin is positive but phase margin is negative

d) Gain margin is negative but phase margin is positive


Q13. A second order under damped system has damping ratio of 0.3. Find the phase margin of the system?

a) 20°

b) 3°

c) 30°

d) 60°


Q14. If the magnitude of G(jω )H(jω ) at phase crossover frequency is 0.5. Find the gain margin of the given system?

a) 0.5

b) 2

c) 1

d) 4


Q15. A second order system has peak over shoot = 50% and period of oscillations 0.2 seconds. Find the resonant frequency?

a) 32.16 rad/s

b) 31.41 rad/s

c) 30.63 rad/s

d) 29.74 ra/s


Q16. The transfer function of a plant is T(s) = 5/(s+5)(s² + 5 + 1). The second order approximation of T(s) using dominant pole concept is

a) 1/(s+1)(s+5)

b) 5/(s+1)(s+5)

c) 1/(s² + 5 + 1)

d) 5/(s² + 5 + 1)


Q17. The phase margin of a system having the loop transfer function G(s)H(s) = 2v^3/s(s+1) is

a) 45°

b) 30°

c) 60°

d) 80° 


Q18. A system has poles at 0.01 Hz, 1 Hz and 80 Hz; zeros at 5 Hz, 100 Hz and 200 Hz. The approximate phase of the system response at 20 Hz is

a) 90°

b) 180°

c) -90°

d) -180°


Q19. A property of phase lead compensation is that the

a) Overshoot is increased

b) Bandwidth of closed loop system is reduced

c) Rise time of closed loop system is reduced

d) Gaim margin is reduced


Q20. Which of the following is the correct expression for the transfer function of an electrical RC phase lag compensating network?

a) RCS/(1+RCS)

b) RC/(1+RCS)

c) C/(1+RCS)

d) 1/(1+RCS) 


Part 4: List for questions and answers of Control System II


Q1. Answer: a


Q2. Answer: d


Q3. Answer: d


Q4. Answer: a


Q5. Answer: b


Q6. Answer: c


Q7. Answer: c


Q8. Answer: a


Q9. Answer: c


Q10. Answer: a


Q11. Answer: b


Q12. Answer: a


Q13. Answer: c


Q14. Answer: b


Q15. Answer: c


Q16. Answer: c


Q17. Answer: b


Q18. Answer: c


Q19. Answer: c


Q20. Answer: d