16. A system has the transfer function (1 – s)/ (1 + s). It is a—
    

1. 1. non-minimum phase system
      

   
   
   

   2. minimum phase system
      

   
   
   

   3. low-pass system
      

   
   
   

   4. second order system

   
   
   

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1. View Hint View Answer Discuss in Forum

   A system with
   

   T.F =	1 - s
   	T + s

   
   is a non-minimum phase system because a non-minimum phase system have at least one pole and/or zero in the R.H. side plane for nonminimum phase system as ω → ∞, phase angle φ ≠ – 90° (n – m). In this case, phase is – tan^–1 ωT – tan^–1 ωT
   = – 2 tan^–1 ωT = – 180° as ω → ∞.

   Correct Option: A

   A system with
   

   T.F =	1 - s
   	T + s

   
   is a non-minimum phase system because a non-minimum phase system have at least one pole and/or zero in the R.H. side plane for nonminimum phase system as ω → ∞, phase angle φ ≠ – 90° (n – m). In this case, phase is – tan^–1 ωT – tan^–1 ωT
   = – 2 tan^–1 ωT = – 180° as ω → ∞.

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17. G(s) =	1 + s
    	s(1 + 0·5s)

    . The corner frequencies are—
    

1. 1. 0 and 1
      

   
   
   

   2. 0 and 2
      

   
   
   

   3. 0 and –1
      

   
   
   

   4. 1 and 2

   
   
   

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1. View Hint View Answer Discuss in Forum

   For the given system
   

   G(s) =	1 + s
   	s (1 + 0.5s)

   
   in order to calculate corner frequency compare given equation with general equation.
   

   G(s) =	(1 + sT1
   	s (1 + sT2)

   
   

   T1 = 1, corner frequency ω1 =	1	=	1	= 1
   	T2		1

   
   

   T2 = 0.5, corner frequency ω2 =	1	=	1	= 2
   	T2		0.5

   Correct Option: D

   For the given system
   

   G(s) =	1 + s
   	s (1 + 0.5s)

   
   in order to calculate corner frequency compare given equation with general equation.
   

   G(s) =	(1 + sT1
   	s (1 + sT2)

   
   

   T1 = 1, corner frequency ω1 =	1	=	1	= 1
   	T2		1

   
   

   T2 = 0.5, corner frequency ω2 =	1	=	1	= 2
   	T2		0.5

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18. The forward transfer function of a system is 10/1 + s. The steady state error to unit step input when operated as a unity feedback system is—
    

1. 1. 10
      

   
   
   

   2. 0
      

   
   
   

   3. 1/11
      

   
   
   

   4. ∞

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given that
   

   G(s) =	10	, H(s)=	1
   	1 + s		s

   
   r (t) = u (t)
   then R (s) = 1/s
   

   ess = s → 0Lim .sE (s) =s → 0Lim	s.R(s)
   	1 + G(s) H(s)

   
   

   =s → 0Lim	s.1/s	=	1
   	1 + 10/1 + s.1		11

   Correct Option: C

   Given that
   

   G(s) =	10	, H(s)=	1
   	1 + s		s

   
   r (t) = u (t)
   then R (s) = 1/s
   

   ess = s → 0Lim .sE (s) =s → 0Lim	s.R(s)
   	1 + G(s) H(s)

   
   

   =s → 0Lim	s.1/s	=	1
   	1 + 10/1 + s.1		11

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19. For a standard feedback control loop, the sensitivity of the closed-loop transfer function T to forward path gain G and feedback path gain H are—
    

    SGT	SHT
    A. -1/(1 + GH)	-1(1 + GH)
    B. -GH/(1 + GH)	-H/(1 + GH)
    C. G/(1 + GH)	1/(1 + GH)
    D. 1/(1 + GH)	-GH/(1 +GH)

1. 1. A

   
   
   

   2. B

   
   
   

   3. C

   
   
   

   4. D

   
   
   

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1. View Hint View Answer Discuss in Forum

   For more detail refer synopsis.

   Correct Option: D

   For more detail refer synopsis.

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20. Consider the following statements with reference to the block diagram of a control system given in the figure
    1. For G₂ = 0, the system is open-loop.
    2. For G₁ = 0, the system is closed-loop.
    3. For G₂ = H = 1, the system is closed-loop Of these statements—
    
    
    
    

1. 1. 1, 2 and 3 are correct
      

   
   
   

   2. 1 and 2 are correct
      

   
   
   

   3. 2 and 3 are correct
      

   
   
   

   4. 1 and 3 are correct

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   
   

   Correct Option: C

   NA

   
   

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