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d c motors MCQs

Practise focused d c motors questions with marked answers for exam preparation and subject revision.

d c motors Mcqs
1. When two D.C. series motors are connected in parallel, the resultant speed is____________?
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A. more than the normal speed

B. normal speed

C. zero

D. loss than the normal speed

2. For starting a D.C. motor a starter is required because___________?
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A. it starts the motor

B. it limits the speed of the motor

C. none of the above

D. it limits the starting current to a safe value
3. Which D.C. motor is preferred for elevators ?
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A. Cumulative compound motor

B. Series motor

C. Differential compound motor

D. Shunt motor

4. The size of poxvirus is_______________?
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A. 250 nm

B. 200 nm

C. 20 nm

D. 300 nm
5. The type of D.C. motor used for shears and punches is_____________?
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A. differential compoutid D.C. motor

B. cumulative compound D.C. motor

C. series motor

D. shunt motor

6. If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
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A. Shunt motor

B. Differentially compound motor

C. Series motor

D. Cumulative compound motor

7. Kingdom Protoctista includes_______________?
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A. Prokaryotic organisms

B. Fungi

C. Eu-cariotiquic organisms

D. Unicellular organisms
8. No-load speed of which of the following motor will be highest ?
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A. Differentiate compound motor

B. Shunt motor

C. Series motor

D. Cumulative compound motor

9. Which D.C. motor will be preferred for machine tools ?
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A. Shunt motor

B. Differential compound motor

C. Series motor

D. Cumulative compound motor

10. If a D.C. motor is connected across the A.C. supply it will_______________?
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A. run at lower speed

B. burn due to heat produced in the field winding by .eddy currents

C. not run

D. run at normal speed

11. Which of the following application requires high starting torque ?
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A. Air blower

B. Locomotive

C. Lathe machine

D. Centrifugal pump

12. Differentially compound D.C. motors can find applications requiring___________?
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A. high starting torque

B. frequent on-off cycles

C. low starting torque

D. variable speed

13. To get the speed of D.C, motor below the normal without wastage of electrical energy is used?
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A. Ward Leonard control

B. none of the above method

C. rheostatic control

D. any of the above method

14. According to Flemings left-hand rule, when the forefinger points in the direction of the field or flux, the middle finger will point in the direction of_________________?
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A. none of the above

B. current in the conductor aovtaat of conductor

C. resultant force on conductor

15. The direction of rotation of a D.C. series motor can be changed by___________?
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A. either of A. and B. above

B. None of the above

C. interchanging field terminals

D. interchanging supply terminals

16. A D.C. series motor is that which______________?
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A. can be started easily without load

B. has its field winding consisting of thick wire and less turns

C. has almost constant speed

D. has a poor torque

17. If the field of a D.C. shunt motor gets opened while motor is running______________?
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A. the motor will continue to nuvat constant speed

B. the armature current will reduce

C. the speed of motor will be reduced %

D. the motor will attain dangerously high speed 1
18. Starters are used with D.C. motors because______________?
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A. back e.m.f. of these motors is zero initially

B. these motors have high starting torque

C. to restrict armature current as there is no back e.m.f. while starting

D. these motors are not self-starting

19. In D.C. shunt motors as load is reduced__________________?
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A. the speed will remain almost/constant

B. the speed will reduce

C. the speed will increase abruptly

D. the speed will increase in proportion to reduction in load

20. D.C. series motors are used______________?
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A. where load changes frequently

B. where constant operating speed is needed

C. where load is constant

D. in none of the above situations