2003

1. The gain margin and the phase margin of a feedback system with G(s)H(s) = s/(s + 100)

a) 0 dB, 0

b) ∞, ∞

c) ∞, 0

d) 88.5 dB, ∞

2004

2. The gain margin for the system with open loop transfer function G(s)H(s) = 2(1 + s)/s

a) ∞

b) 0

c) 1

d) - ∞

2005

The open loop transfer function of a unity feedback is given by G(s) = 3e

3. The Gain and Phase cross over frequencies in rad/sec are, respectively

a) 0.932 and 1.26

b) 0.632 and 0.485

c) 0.485 and 0.632

d) 1.26 and 0.632

4. based on the above results, the Gain and Phase Margins of the system will be

a) –7.09 dB and 87.5

b) 7.09 dB and 87.5

c) 7.09 dB and –87.5

d) –7.09 dB and –87.5

2006

5. The open loop transfer function of a unity gain feedback control system is given by G(s) = K

a) 0

b) 1

c) 20

d) ∞

Consider a unity gain feedback control system whose open loop transfer function is G(s) = (as + 1)

6. The value of "a" so that the system has a phase margin equal to π/4 is approximately equal to

a) 2.40

b) 1.40

c) 0.84

d) 0.74

7. With the value of "a" set for phase margin of π/4, the value of unit impulse response of the open loop system at t = 1 second is equal to

a) 3.40

b) 2.40

c) 1.84

d) 1.74

2011

The input – output transfer function of a plant H(s) = 100/s(s+10)

8. The signal flow graph that DOES NOT model the plant transfer function H(s) is

9. The gain margin of the system under closed loop unity negative feedback is

a) 0 dB

b) 20 dB

c) 26 dB

d) 46 dB

2012

10. A system with transfer function is excited by sin(ωt).

The steady state output of the system is zero at

a) ω = 1 rad/sec

b) ω = 2 rad/sec

c) ω = 3 rad/sec

d) ω = 4 rad/sec

2014

11. The phase margin in degrees of

calculated using the asymptotic Bode plot is ____________

2015

12. The phase margin (in degrees ) of the system G(s) = 10 /s(s+10) is _____________

1. The gain margin and the phase margin of a feedback system with G(s)H(s) = s/(s + 100)

^{3 }area) 0 dB, 0

^{o}b) ∞, ∞

c) ∞, 0

^{o}d) 88.5 dB, ∞

**Solution :****https://www.youtube.com/watch?v=n44i9T5koz4**2004

2. The gain margin for the system with open loop transfer function G(s)H(s) = 2(1 + s)/s

^{2}, isa) ∞

b) 0

c) 1

d) - ∞

**Solution :**https://www.youtube.com/watch?v=L2Y_rS_Zc9M2005

**Statement for Linked Answer Questions 3 & 4:**The open loop transfer function of a unity feedback is given by G(s) = 3e

^{–2s }**/**[s(s + 2)].3. The Gain and Phase cross over frequencies in rad/sec are, respectively

a) 0.932 and 1.26

b) 0.632 and 0.485

c) 0.485 and 0.632

d) 1.26 and 0.632

**Solution :**https://www.youtube.com/watch?v=eKZo_zPxjYI4. based on the above results, the Gain and Phase Margins of the system will be

a) –7.09 dB and 87.5

^{o}b) 7.09 dB and 87.5

^{o}c) 7.09 dB and –87.5

^{o}d) –7.09 dB and –87.5

^{o}**Solution :**https://www.youtube.com/watch?v=aHVPuRMM0q82006

5. The open loop transfer function of a unity gain feedback control system is given by G(s) = K

**/**[(s + 1)(s + 2)]. The gain margin of the system in dB is given bya) 0

b) 1

c) 20

d) ∞

**Solution :**https://www.youtube.com/watch?v=_GEVQWlLBOs

**Statement for Linked Answer questions: (6 and 7)**Consider a unity gain feedback control system whose open loop transfer function is G(s) = (as + 1)

**/**s^{2}.6. The value of "a" so that the system has a phase margin equal to π/4 is approximately equal to

a) 2.40

b) 1.40

c) 0.84

d) 0.74

7. With the value of "a" set for phase margin of π/4, the value of unit impulse response of the open loop system at t = 1 second is equal to

a) 3.40

b) 2.40

c) 1.84

d) 1.74

**Solution (10 & 11) :**https://www.youtube.com/watch?v=DlzZDVlirog2011

**Common Data Questions 8 & 9:**The input – output transfer function of a plant H(s) = 100/s(s+10)

^{2}. The plant is placed in a unity negative feedback configuration as shown in figure below.8. The signal flow graph that DOES NOT model the plant transfer function H(s) is

**Solution :**https://www.youtube.com/watch?v=gSg5jPv06fQ9. The gain margin of the system under closed loop unity negative feedback is

a) 0 dB

b) 20 dB

c) 26 dB

d) 46 dB

**Solution :**https://www.youtube.com/watch?v=HreyReFPqag2012

10. A system with transfer function is excited by sin(ωt).

The steady state output of the system is zero at

a) ω = 1 rad/sec

b) ω = 2 rad/sec

c) ω = 3 rad/sec

d) ω = 4 rad/sec

**Solution :**https://www.youtube.com/watch?v=UYEEuh71lxc2014

11. The phase margin in degrees of

calculated using the asymptotic Bode plot is ____________

**Solution :**https://www.youtube.com/watch?v=ZwdvClI0_mU2015

12. The phase margin (in degrees ) of the system G(s) = 10 /s(s+10) is _____________

**Solution :**https://www.youtube.com/watch?v=WXHKVhdLeOc