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
Hysteresis motor is particularly useful for high-quality record players and tape-recorders because
A it revolves synchronously
B it is not subject to any magnetic or mechanical vibrations
C it can be easily manufactured in extremely small sizes of up to 1 W output
D it develops hysteresis torque which is extremely steady both in amplitude and phase
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
A hysteresis motor works on the principle of
A hysteresis loss
B magnetisation of rotor
C eddy current loss
D electromagnetic induction
In a hysteresis motor, the rotor must have
A retentivity
B resistivity
C susceptibility
D none of the above
Which one of the following statements best describes magnetic hysteresis?
A Hysteresis is the amount of magnetic flux that is not confined to the core material of an electromagnet
B Hysteresis is most apparent when a steady amount of current is lowing through the coil of an electromagnet
C Hysteresis is most apparent when the current through the coil of an electromagnet changes frequently
D Hysteresis is most apparent when the core material is saturated
E None of the above
No eddy current and hysteresis losses occur in
A Electrostatic instruments
B PMMC instruments
C Moving iron instruments
D Electrodynamo meter instruments
The phenomenon of dielectric hysteresis occurs with
A DC
B AC
C Both AC and DC
D None of the above
Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator?
A Providing laminations in armature core
B Providing laminations in stator
C Using nonmagnetic material for frame
D Using material of low hysteresis coefficient for armature core material
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

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