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D.C. Motors - section-1
  1. The armature torque of the D.C. shunt motor is proportional to

    2. A.

     field flux only
    B.

     armature current only
    C.

     both (A) and (B)
    D.

     none of the above

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  2. What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?

    3. A.

     The motor will stop
    B.

     The motor will continue to run
    C.

     The armature may burn
    D.

     The motor will run noisy

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  3. If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens

    4. A.

     This will make armature to take heavy current, possibly burning it
    B.

     This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
    C.

     Nothing will happen to motor
    D.

     Motor will come to stop

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  4. If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens

    5. A.

     Nothing will happen to the motor
    B.

     This will make armature to take heavy current, possibly burning it
    C.

     This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
    D.

     Motor will run at very slow speed

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  5. The main disadvantage of the Ward-Leonard control method is

    6. A.

     High initial cost
    B.

     High maintenance cost
    C.

     Low efficiency at high loads
    D.

     All of the above

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  6. D.C. series motors are used

    7. A.

     Where load is constant
    B.

     Where load changes frequently
    C.

     Where constant operating speed is needed
    D.

     In none of the above situations

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  7. Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?

    8. A.

     Low cost
    B.

     Wide speed range
    C.

     Stability
    D.

     High starting torque

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  8. Three point starter can be used for

    9. A.

     Series motor only
    B.

     Shunt motor only
    C.

     Compound motor only
    D.

     Both shunt and compound motor

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  9. These days D.C. motors are widely used in

    10. A.

     Pumping sets
    B.

     Air compressors
    C.

     Electric traction
    D.

     Machine shops

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  10. In D.C. shunt motors as load is reduced

    11. A.

     The speed will increase abruptly
    B.

     The speed will increase in proportion to reduction in load
    C.

     The speed will remain almost/constant
    D.

     The speed will reduce

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