Related Questions

If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be
A Zero
B Small
C Large
D None of the above
Mr. Ali decided to walk down the escalator of a tube station. He found that if he walks down 26 steps, he requires 30 seconds to reach the bottom. However, if he steps down 34 stairs he would only require 18 seconds to get to the bottom. If the time is measured from the moment the top step begins to descend to the time he steps off the last step at the bottom, find out the height of the stair way in steps?
A 23 steps
B 16 steps
C 46 steps
D 26 steps
The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator?
A Hysteresis loss
B Field copper loss
C Armature copper loss
D Eddy current loss
Hysteresis loss and eddy current loss are used in
A Induction heating of steel
B Dielectric heating
C Induction heating of brass
D Resistance heating
As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately
A 40 percent
B 25 percent
C 10 percent
D 5 percent
In a magnetic material hysteresis loss takes place primarily due to
A Rapid reversals of its magnetization
B Flux density lagging behind magnetizing force
C Molecular friction
D It high retentivity
The hysteresis loss in a D.C. machine least depends on
A Frequency of magnetic reversals
B Maximum value of flux density
C Volume and grade of iron
D Rate of flow of ventilating air
Hysteresis loss least depends on
A Volume of material
B Frequency
C Steinmetz’s coefficient of material
D Ambient temperature
Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator?
A Dummy coils
B Commutator
C Eye bolt
D Equalizer rings
The e.m.f. generated by a shunt wound D.C. generator is E. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be
A $$\frac{{\text{E}}}{2}$$
B 2E
C Slightly less than E
D E

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