Torque Developed in D.C Motor - MCQs with Answers

Torque Developed in D.C Motor - MCQs with Answers

Q1. A 4 pole, lap wound d.c. motor drawing an armature current of 20 A has 360 conductors. If the flux per pole is 0.015 Wb then the gross torque developed by the armature of motor is

a. 10.23 N-m
b. 15.56 N-m
c. 17.17 N-m
d. 19.08 N-m

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Q2. If the no load speed of d.c. motor is 1350 rpm and full load speed is 1150 rpm, then its voltage regulation is

a. 11.56%
b. 15.36 %
c. 17.39%
d. 19.39%

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Q3. As the load on d.c. motor increases, the current drawn by motor

a. Increases
b. Decreases
c. Remains same
d. None of these

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Q4. If the back emf of a d.c. motor is doubled and flux is halved (keeping other parameters constant) then its speed will become

a. Double of the original speed
b. Square of the original speed
c. Four times of the original speed
d. Half of the original speed

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Q5. Keeping the field excitation constant, the constant of proportionality between back emf and armature speed of d.c. motor is

a. Twice of the proportionality constant between developed torque and armature current
b. Half of the proportionality constant between developed torque and armature current
c. Same as that of proportionality constant between developed torque and armature current
d. None of these

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