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In 0.0. machine the yoke is made of
A) Cast steel
C) Silicon steel

B) Soft iron
D) None of the above

The armature of a d.c. machine is laminated in order to reduce
A) Copper loss B) Eddy current loss
C) Hysteresis loss D) Frictional loss

In 6.0. machine the armature winding is placed on rotor to
A) Reduce the armature reaction B) Facilitate commutation
C) Save iron D) Reduce losses

11 8 ೮.೦. machine, the number of armature segments is equal to
A) Number of conductors B) Twice the number of poles
C) Number of coils D) None of the above

The parallel paths of an 8 pole duplex lap winding will be

A) 4 B) 8 016 D) 32

Carbon brushes are preferable to copper brushes due to
A) They have longer life B) They reduce armature reaction
C) They have lower resistance D) They reduce sparking

The speed 0
A) Applied voltage
C) Armature circuit resistance

8 6.0. motor can be controlled by
B) Its flux
D) All of the above

Motor starters are essential for
A) Starting the motor
C) Avoiding excessive starting current

B) Accelerating the motor
D) Preventing fuse blowing

The efficiency of a d.c. motor when developing maximum mechanical power will be
A) Less than50% 8) 50% C) More than 50% 0) 100%

If the load current and magnetic flux of a d.c. motor are held constant and voltage
applied across its armature is increased by 5%, the speed of the motor will

A) Remain unaltered
C) Depend on other factors

B) Decrease by 5%
D) Increase by 5%

The primary and secondary of a transformer are coupled

A) Electrically
C) Electrically and magnetically

B) Magnetically
D) None of the above

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