Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Control System 10

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

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**Q1. The lag compensator**

**a) Increases the damping ratio**

**b) Decreases the damping ratio**

**c) Increases the band width**

**d) Increases the stability**

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**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**

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**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**

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**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**

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**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 **

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**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**

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

**a) 20 log2ξ **

**b) 10 log2ξ **

**c) -20 log2ξ **

**d) -10 logξ **

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**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**

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**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**

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**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**

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**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 **

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**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**

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**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°**

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**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**

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**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**

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**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)**

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**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° **

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**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°**

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**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**

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**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) **

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

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**Q1. Answer: a**

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**Q2. Answer: d**

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**Q3. Answer: d**

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**Q4. Answer: a**

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**Q5. Answer: b**

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**Q6. Answer: c**

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**Q7. Answer: c**

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**Q8. Answer: a**

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**Q9. Answer: c**

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**Q10. Answer: a**

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**Q11. Answer: b**

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**Q12. Answer: a**

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**Q13. Answer: c**

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**Q14. Answer: b**

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**Q15. Answer: c**

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**Q16. Answer: c**

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**Q17. Answer: b**

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**Q18. Answer: c**

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**Q19. Answer: c**

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**Q20. Answer: d**