DC Motors

Which of the following rule is used to determine the direction of rotation of D.C motor?

• Coloumb’s Law

• Lenz’s Law

• Fleming’s Right-hand Rule

• Fleming’s Left-hand Rule

A three-point starter is suitable for

• Shunt Motor

• Series Motor

• Shunt & Compound Motor

• Shunt, Series, and compound motor

Nowadays DC motor is widely used in

• Electric Traction

• Air compressor

• Centrifugal Pump

• Machine shop

Counter EMF of the DC motor is

• Less than the applied voltage

• More than the applied voltage

• Equal to the applied voltage

• None of the above

If the back EMF of DC motor vanishes then

• The motor continues to run

• Motor will stop

• Armature will burn

• The motor continues to run in slow speed

What will happen when the field of a DC shunt motor gets opened while the motor is running?

• Continue to run at the same speed

• Speed of motor will be reduced

• The motor will attain dangerous high speed

• Armature current will be reduced

The reason for using starter while starting of DC motor is

• To restrict armature current as there is no back E.M.F at starting

• Motors are not self-starting

• Restrict starting torque

• None of the above

The application of Differentially compound motor is

• Frequent on-off cycle

• Low starting torque

• High starting torque

• Variable speed

Which of the following application requires high starting torque?

• Air blower

• Elevator

• Locomotive

• Centrifugal Pump

Which DC motor is preferred for constant speed?

• Series motor

• Compound motor

• Shunt motor

• Differential motor