The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?

A. 2.36%
B. 4.76%
C. 6.77%
D. 8.84%

Usually wide and sensitive speed control is desired in case of____________?

A. Centrifugal pumps
B. Elevators
C. Steel rolling mills
D. Colliery winders

Which of the following method of speed control of D.C. machine will offer minimum efficiency ?

A. Voltage control method
B. Field control method
C. Armature control method
D. All above methods

The armature torque of the D.C. shunt motor is proportional to____________?

A. Field flux only
B. Armature current only
C. Both a. and b.
D. None of the above

As -the load is increased the speed of D.C. shunt motor will____________?

A. Reduce slightly
B. Increase slightly
C. Increase proportionately
D. Remains unchanged

Which of the following motor has the poorest speed regulation ?

A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor

Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of_____________?

A. D.c. series motor
B. D.c. shunt motor
C. Induction motor
D. All of above motors

The condition for maximum power in case of D.C. motor is______________?

A. Back e.m.f. = 2 x supply voltage
B. Back e.m.f. = | x supply voltage
C. Supply voltage = | x back e.m.f
D. Supply voltage = back e.m.f

In a differentially compounded D.C. motor, if shunt field suddenly opens____________?

A. The motor will first stop and then run in opposite direction as series motor
B. The motor will work as series motor and run at slow speed in the same direction
C. The motor will work as series motor and run at high speed in the same direction
D. The motor will not work and come to stop

Following motor is used where high starting torque and wide speed range control is required?

A. Single phase capacitor start
B. Induction motor
C. Synchronous motor
D. c. motor