1. If 1.8° step, 4-phase stepper motor has a total of 40 teeth on 8 poles of startor, then number of rotor teeth for this motor will be
   

1. 1. 40

   
   
   

   2. 50

   
   
   

   3. 100

   
   
   

   4. 80

   
   
   

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   NA

   Correct Option: C

   NA

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2. If an a.c. servomotor has one of its winding excited by a.c., t hen voltage measured at the other winding with rotor running will be
   

1. 1. zero

   
   
   

   2. proportional to rotor speed

   
   
   

   3. proportional to the square of the rotor speed

   
   
   

   4. constant independent of speed.

   
   
   

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   NA

   Correct Option: B

   NA

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3. An ac servomotor exhibits
   

1. 1. two time constants which depend upon rotor inertia and mechanical friction

   
   
   

   2. two time constants which depend upon rotor inertia, the slope of its torque speed characteristic and mechanical friction.

   
   
   

   3. a dominant time constant which depends upon rotor inertia and mechanical friction

   
   
   

   4. a dominant time constant which depends upon rotor inertia, the slope of its torque-speed characteristic and mechanical friction.

   
   
   

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   NA

   Correct Option: D

   NA

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4. In an ac servometer, the control winding is supplied with input voltage of
   

1. 1. same frequency as the reference winding voltage but with 90° phase difference.

   
   
   

   2. same frequency as the reference windings voltage and also having same phase.

   
   
   

   3. any frequency compared to t he reference winding but with 90° phase difference.

   
   
   

   4. any frequency compared to the reference winding but of the same phase.

   
   
   

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   NA

   Correct Option: A

   NA

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5. A two-phase servomotor develops maximum torque at
   

1. 1. forward speed of one-half of the synchronous speed

   
   
   

   2. backward speed of one-half of the synchronous speed

   
   
   

   3. synchronous speed

   
   
   

   4. a speed of twice the synchronous speed
      

   
   
   

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   NA

   Correct Option: A

   NA

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