Magnetic Circuit 1(TTA)
. INSTRUCTIONS
1. NUMBER OF QUESTIONS 22
2. HAS A TIME LIMIT OF 20 MINUTES
3. HAS A PASS MARKS OF 30%
4. QUESTIONS PER PAGE 1
5. EACH QUESTIONS HAS 1 MARKS
6. NEGATIVE MARKING FOR EACH QUESTIONS 0.25
7. WILL ALLOW TO YOU GO BACK ,SKIP AND CHANGE YOUR ANSWERS
8. WILL ALLOW TO YOU PRINT OUT YOUR RESULT AND CERTIFICATE
9. WILL ALLOW TO YOU PRINT OUT YOURS RESPONSE SHEET WITH CORRECT ANSWER KEY AND EXPLANATION
10. WE WILL PROVIDE YOURS RESULT,CERTIFICATE AND YOUR RESPONSE SHEET TO YOURS EMAIL ID AT END OF ONLINE TEST
- 1.
The unit of reluctance is
- A.
Meter/Henry
- B.
Henry/Meter
- C.
Henry
- D.
1/Henry
Correct Answer
C. Henry -
- 2.
Those materials are well suited for making permanent magnets which have______retentivity and _______coercivity.
- A.
Low, high
- B.
High, high
- C.
High, low
- D.
Low, low
Correct Answer
B. High, high -
- 3.
While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ?
- A.
E.m.f.
- B.
Current
- C.
Current density
- D.
Conductivity
Correct Answer
B. Current -
- 4.
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
Correct Answer
B. At the start of the current flow -
- 5.
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
Correct Answer
C. Large -
- 6.
The unit of retentivity is
- A.
Weber
- B.
Weber/sq. m
- C.
Ampere turn/metre
- D.
Ampere turn
Correct Answer
B. Weber/sq. m -
- 7.
Silicon steel is used in electrical machines because it has
- A.
Low co-ercivity
- B.
Low retentivity
- C.
Low hysteresis loss
- D.
High co-ercivity
Correct Answer
C. Low hysteresis loss -
- 8.
Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it
- A.
Lowers their power efficiency
- B.
Increases their cost of manufacture
- C.
Leads to their increased weight
- D.
Produces fringing
Correct Answer
A. Lowers their power efficiency -
- 9.
Permeability in a magnetic circuit corresponds to______ in an electric circuit.
- A.
Resistance
- B.
Resistivity
- C.
Conductivity
- D.
Conductance
Correct Answer
C. Conductivity -
- 10.
A material for good magnetic memory should have
- A.
Low hysteresis loss
- B.
High permeability
- C.
Low retentivity
- D.
High retentivity
Correct Answer
D. High retentivity -
- 11.
.Permanent magnets are normally made of
- A.
Alnico alloys
- B.
Aluminium
- C.
Cast iron
- D.
Wrought iron
Correct Answer
A. Alnico alloys -
- 12.
Relative permeability of vacuum is
- A.
1
- B.
1 H/m
- C.
1/4JI
- D.
4n x 10-' H/m
Correct Answer
A. 1 -
- 13.
When both the inductance and resistance of a coil are doubled the value of
- A.
Time constant remains unchanged
- B.
Initial rate of rise of current is doubled
- C.
Final steady current is doubled
- D.
Time constant is halved
Correct Answer
A. Time constant remains unchanged -
- 14.
.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
Correct Answer
D. Ferrites have high hysteresis -
- 15.
Conductance is analogous to
- A.
Permeance
- B.
Reluctance
- C.
Flux
- D.
Inductance
Correct Answer
A. Permeance -
- 16.
Hard steel is suitable for making permanent magnets because
- A.
It has good residual magnetism
- B.
Its hysteresis loop has large area
- C.
Its mechanical strength is high
- D.
Its mechanical strength is low
Correct Answer
A. It has good residual magnetism -
- 17.
Conductivity is analogous to
- A.
Retentivity
- B.
Resistivity
- C.
Permeability
- D.
Inductance
Correct Answer
C. Permeability -
- 18.
The property of a material which opposes the creation of magnetic flux in it is known as
- A.
Reluctivity
- B.
Magnetomotive force
- C.
Permeance
- D.
Reluctance
Correct Answer
D. Reluctance -
- 19.
In a magnetic material hysteresis loss takes place primarily due to
- A.
Rapid reversals of its magnetisation
- B.
Flux density lagging behind magnetising force
- C.
Molecular friction
- D.
It high retentivity
Correct Answer
D. It high retentivity -
- 20.
The unit of magnetic flux is
- A.
Henry
- B.
Weber
- C.
Ampereturn/weber
- D.
Ampere/metre
Correct Answer
B. Weber -
- 21.
Laminated cores, in electrical machines, are used to reduce
- A.
Copper loss
- B.
Eddy current loss
- C.
Hysteresis loss
- D.
All of the above
Correct Answer
B. Eddy current loss -
- 22.
Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss.
- A.
High,high
- B.
Low,high
- C.
High,low
- D.
Low,low
Correct Answer
C. High,low -
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Current Version
-
Mar 20, 2022Quiz Edited by
ProProfs Editorial Team -
Jul 23, 2016Quiz Created by
Harish.hot04
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