26. The type of a transfer function denotes the number of—
    

1. 1. Poles at origin
      

   
   
   

   2. Zeros at origin
      

   
   
   

   3. Finite poles
      

   
   
   

   4. Poles at infinity

   
   
   

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1. View Hint View Answer Discuss in Forum

   The type of a transfer function denotes the number of poles at origin.
   

   Correct Option: A

   The type of a transfer function denotes the number of poles at origin.
   

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27. Which input yields natural response?
    

1. 1. ac input
      

   
   
   

   2. dc input
      

   
   
   

   3. impulse input
      

   
   
   

   4. a ramp input

   
   
   

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1. View Hint View Answer Discuss in Forum

   Impulse input yields natural response.

   Correct Option: C

   Impulse input yields natural response.

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28. G (s) =	1
    	s(1 + 6s)

    
    the system is—
    

1. 1. stable
      

   
   
   

   2. unstable
      

   
   
   

   3. marginally stable
      

   
   
   

   4. conditionally stable

   
   
   

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1. View Hint View Answer Discuss in Forum

   The poles at the origin, the phase angle may extend upto – 180º, limits the stability. Hence the system is marginally stable.

   Correct Option: C

   The poles at the origin, the phase angle may extend upto – 180º, limits the stability. Hence the system is marginally stable.

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29. A minimum-phase system with no zeros has a phase angle of – 270° at gain crossover frequency. The system is—
    

1. 1. stable
      

   
   
   

   2. unstable
      

   
   
   

   3. marginally stable
      

   
   
   

   4. conditionally stable

   
   
   

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1. View Hint View Answer Discuss in Forum

   Since the phase margin is negative hence system is unstable.

   Correct Option: B

   Since the phase margin is negative hence system is unstable.

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30. Sinusoidal oscillator are—
    

1. 1. stable
      

   
   
   

   2. marginally stable
      

   
   
   

   3. unstable
      

   
   
   

   4. conditionally stable

   
   
   

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1. View Hint View Answer Discuss in Forum

   Sinusoidal oscillators are always marginally stable.
   

   Correct Option: B

   Sinusoidal oscillators are always marginally stable.
   

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