Practice Test: Question Set - 01
1. Those magnetic materials are best suited for making armature and transformer cores which have ________permeability and _________hysteresis loss.
- (A) High, high
- (B) Low, high
- (C) High, low
- (D) Low, low
2. 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
3. Silicon steel is used in electrical machines because it has
- (A) Low coercivity
- (B) Low retentivity
- (C) Low hysteresis loss
- (D) High coercivity
4. Reciprocal of reluctance is
- (A) Reluctivity
- (B) Permeance
- (C) Permeability
- (D) Susceptibility
5. Hysteresis loss least depends on
- (A) Volume of material
- (B) Frequency
- (C) Steinmetz’s coefficient of material
- (D) Ambient temperature
6. An air gap is usually inserted in magnetic circuits to
- (A) Increase m.m.f.
- (B) Increase the flux
- (C) Prevent saturation
- (D) None of the above
7. The rate of rise of current through an inductive coil is maximum
- (A) At 63.2% of its maximum steady value
- (B) At the start of the current flow
- (C) After one time constant
- (D) Near the final maximum value of current
8. Conductivity is analogous to
- (A) Retentivity
- (B) Resistivity
- (C) Permeability
- (D) Inductance
9. The property of a material which opposes the creation of magnetic flux in it is known as
- (A) Reluctivity
- (B) Magneto-motive force
- (C) Permeance
- (D) Reluctance
10. A ferrite core has less eddy current loss than an iron core because
- (A) Ferrites have high resistance
- (B) Ferrites are magnetic
- (C) Ferrites have low permeability
- (D) Ferrites have high hysteresis
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