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D.C Motor: [ ISRO,DRDO,DMRC,SAIL, ODNANCE, HAL, WBSEDCL, RAILWAY & Others competitive] DC Motor MCQ Questions And Answers

1. Starters are used with D.C. motors because….

(a) these motors have high starting torque

(b) these motors are not self-starting

(c) back e.m.f. of these motors is zero initially

(d) to restrict armature current as there is no back e.m.f. while starting

Ans: d

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2. In D.C. shunt motors as load is reduced……

(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

Ans: c

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3. A D.C. series motor is that which  …….

(a) has its field winding consisting of thick wire and less turns

(b) has a poor torque

(c) can be started easily without load

(d) has almost constant speed

Ans: a

4. For starting a D.C. motor a starter is required because………

(a) it limits the speed of the motor

(b) it limits the starting current to a safe value

(c) it starts the motor

(d) none of the above

Ans: b

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5. The type of D.C. motor used for shears and punches is……….

(a) shunt motor

(b) series motor

(c) differential compound D.C. motor https://youtu.be/IknfOS2f4qA

(d) cumulative compound D.C. motor

Ans: d

6. If a D.C. motor is connected across the A.C. supply it will……….

(a) run at normal speed

(b) not run

(c) run at lower speed

(d) burn due to heat produced in the field winding by eddy currents

Ans: d

7. To get the speed of D.C, motor below the normal without wastage of electrical energy is used.……….

(a) Ward Leonard control

(b) rheostatic control

(c) any of the above method

(d) none of the above method

Ans: a

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8. When two D.C. series motors are connected in parallel, theresultant speed is……….

(a) more than the normal speed

(b) loss than the normal speed

(c) normal speed

(d) zero

Ans: c

9. The speed of a D.C. shunt motor more than its full-load speed can be obtained by……….

(a) decreasing the field current

(b) increasing the field current

(c) decreasing the armature current

(d) increasing the armature current

Ans: a

10. In a D.C. shunt motor, speed is……….

(a) independent of armature current

(b) directly proportional to the armature current

(c) proportional to the square of the current

(d) inversely proportional to the armature current

Ans: a

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