# 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 2021 and IES 2021 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 ANSWER : : Fleming's left-hand rule Explanation :
 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 ANSWER : : 0.5 Explanation :
 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. ANSWER : : back e.m.f. = | x supply voltage Explanation :
 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 ANSWER : : to reduce the sparking Explanation :
 10.For the same H.P. rating and full load speed, following motor has poor starting torque shunt series differentially compounded cumulativelyc'ompounded ANSWER : : differentially compounded Explanation :

More Dc Motors QUESTIONS AND ANSWERS available in next pages

Health is the greatest gift, contentment is the greatest wealth -Buddha
The only place where success comes before work is in the dictionary.- Vidal Sassoon