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Dc Motors QUESTIONS AND ANSWERS

Electrical Engineering : Dc Motors QUESTIONS AND ANSWERS :: part3 : 16 to 20

Following Electrical Engineering Multiple choice objective type questions and answers will help you in BSNL JTO, GATE 2024 and IES 2024 examinations :

16.For a D.C. shunt motor if the excitation is changed

torque will remain constant

torque will change but power will remain constant

torque and power both will change

torque, power and speed, all will change

17.Usually wide and sensitive speed control is desired in case of

centrifugal pumps

elevators

steel rolling mills

colliery winders

18.As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit

a resistance is connected in series with armature

a resistance is connected parallel to the armature

armature is temporarily open circuited

a high value resistor is connected across the field winding

19.In a differentially compounded D.C. motor, if shunt field suddenly opens

the motor will first stop and then run in opposite direction as series motor

the motor will work as series motor and run at slow speed in the same direction

the motor will work as series motor and run at high speed in the same direction

the motor will not work and come to stop

20.The speed of a D.C. shunt motor can be increased by

increasing the resistance in armature circuit

increasing the resistance in field circuit