Electrical Engineering Questions And Answers :: Dc Motors: part2



Electrical Engineering : Dc Motors QUESTIONS AND ANSWERS :: part2 : 6 to 10

Following Electrical Engineering Multiple choice objective type questions and answers will help you in BSNL JTO, GATE 2014 and IES 2014 examinations :

6.Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ?

Lenz's law
Faraday's law
Coloumb's law
Fleming's left-hand rule

7.The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is

4.0
2.0
1.0
0.5

8.The condition for maximum power in case of D.C. motor is

back e.m.f. = 2 x supply voltage
back e.m.f. = | x supply voltage
supply voltage = | x back e.m.f.
supply voltage = back e.m.f.

9.In D.C. machines fractional pitch winding is used

to improve cooling
to reduce copper losses
to increase the generated e.m.f.
to reduce the sparking

10.For the same H.P. rating and full load speed, following motor has poor starting torque

shunt
series
differentially compounded
cumulativelyc'ompounded

More Dc Motors QUESTIONS AND ANSWERS available in next pages

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