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This section includes 56 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
1. |
Conductivity is analogous to |
A. | etentivity |
B. | esistivity |
C. | ermeability |
D. | nductance |
Answer» D. nductance | |
2. |
The property of a material which opposes the creation of magnetic flux in it is known as |
A. | eluctivity |
B. | agneto-motive force |
C. | ermeance |
D. | eluctance |
Answer» E. | |
3. |
The rate of rise of current through an inductive coil is maximum |
A. | t 63.2% of its maximum steady value |
B. | t the start of the current flow |
C. | fter one time constant |
D. | ear the final maximum value of current |
Answer» C. fter one time constant | |
4. |
Hysteresis loss least depends on |
A. | olume of material |
B. | requency |
C. | teinmetz’s coefficient of material |
D. | mbient temperature |
Answer» E. | |
5. |
The unit of reluctance is |
A. | eter/Henry |
B. | enry/meter |
C. | enry |
D. | /Henry |
Answer» E. | |
6. |
Hard steel is suitable for making permanent magnets because |
A. | t has good residual magnetism |
B. | ts hysteresis loop has large area |
C. | ts mechanical strength is high |
D. | ts mechanical strength is low |
Answer» B. ts hysteresis loop has large area | |
7. |
Reciprocal of reluctance is |
A. | eluctivity |
B. | ermeance |
C. | ermeability |
D. | usceptibility |
Answer» C. ermeability | |
8. |
A material for good magnetic memory should have |
A. | ow hysteresis loss |
B. | igh permeability |
C. | ow retentivity |
D. | igh retentivity |
Answer» E. | |
9. |
Permanent magnets are normally made of |
A. | lnico alloys |
B. | luminium |
C. | ast iron |
D. | rought iron |
Answer» B. luminium | |
10. |
Conductance is analogous to |
A. | ermeance |
B. | eluctance |
C. | lux |
D. | nductance |
Answer» B. eluctance | |
11. |
An air gap is usually inserted in magnetic circuits to |
A. | ncrease m.m.f. |
B. | ncrease the flux |
C. | revent saturation |
D. | one of the above |
Answer» D. one of the above | |
12. |
The unit of retentivity is |
A. | eber |
B. | eber/sq. m |
C. | mpere turn/meter |
D. | mpere turns |
Answer» C. mpere turn/meter | |
13. |
Silicon steel is used in electrical machines because it has |
A. | ow coercivity |
B. | ow retentivity |
C. | ow hysteresis loss |
D. | igh coercivity |
Answer» D. igh coercivity | |
14. |
In a magnetic material hysteresis loss takes place primarily due to |
A. | apid reversals of its magnetization |
B. | lux density lagging behind magnetizing force |
C. | olecular friction |
D. | t high retentivity |
Answer» E. | |
15. |
The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is ___________Vs |
A. | 0 |
B. | 0 |
C. | 0.05 |
D. | 00 |
Answer» C. 0.05 | |
16. |
Laminated cores, in electrical machines, are used to reduce |
A. | opper loss |
B. | ddy current loss |
C. | ysteresis loss |
D. | ll of the above |
Answer» C. ysteresis loss | |
17. |
Energy stored by a coil is doubled when its current is increased by percent. |
A. | 25 |
B. | 50.14 |
C. | 41.4 |
D. | 100 |
Answer» D. 100 | |
18. |
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 |
Answer» D. None of the above | |
19. |
Permeability in a magnetic circuit corresponds to_________ in an electric circuit. |
A. | Resistance |
B. | Resistivity |
C. | Conductivity |
D. | Conductance |
Answer» D. Conductance | |
20. |
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 |
Answer» C. High, low | |
21. |
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 |
Answer» B. Increases their cost of manufacture | |
22. |
Conductivity is analogous to%! |
A. | Retentivity |
B. | Resistivity |
C. | Permeability |
D. | Inductance |
Answer» D. Inductance | |
23. |
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 |
Answer» E. | |
24. |
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 |
Answer» C. After one time constant | |
25. |
Permeability in a magnetic circuit corresponds to_________ in an electric circuit.%! |
A. | Resistance |
B. | Resistivity |
C. | Conductivity |
D. | Conductance |
Answer» D. Conductance | |
26. |
Reciprocal of reluctance is%! |
A. | Reluctivity |
B. | Permeance |
C. | Permeability |
D. | Susceptibility |
Answer» C. Permeability | |
27. |
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 |
Answer» D. None of the above | |
28. |
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 |
Answer» C. High, low | |
29. |
*$_Reciprocal of reluctance is? |
A. | Reluctivity |
B. | Permeance |
C. | Permeability |
D. | Susceptibility |
Answer» C. Permeability | |
30. |
*$_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 |
Answer» D. None of the above | |
31. |
*$_Permeability in a magnetic circuit corresponds to_________ in an electric circuit.? |
A. | Resistance |
B. | Resistivity |
C. | Conductivity |
D. | Conductance |
Answer» D. Conductance | |
32. |
*$_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 |
Answer» C. High, low | |
33. |
*/*_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 |
Answer» E. | |
34. |
*/*_A material for good magnetic memory should have? |
A. | Low hysteresis loss |
B. | High permeability |
C. | Low retentivity |
D. | High retentivity |
Answer» E. | |
35. |
*/*_The unit of retentivity is? |
A. | Weber |
B. | Weber/sq. m |
C. | Ampere turn/meter |
D. | Ampere turns |
Answer» C. Ampere turn/meter | |
36. |
*/*_Laminated cores, in electrical machines, are used to reduce? |
A. | Copper loss |
B. | Eddy current loss |
C. | Hysteresis loss |
D. | All of the above |
Answer» C. Hysteresis loss | |
37. |
%_A material for good magnetic memory should have_% |
A. | Low hysteresis loss |
B. | High permeability |
C. | Low retentivity |
D. | High retentivity |
Answer» E. | |
38. |
%_The unit of retentivity is_% |
A. | Weber |
B. | Weber/sq. m |
C. | Ampere turn/meter |
D. | Ampere turns |
Answer» C. Ampere turn/meter | |
39. |
%_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 |
Answer» E. | |
40. |
_ Laminated cores, in electrical machines, are used to reduce$? |
A. | Copper loss |
B. | Eddy current loss |
C. | Hysteresis loss |
D. | All of the above |
Answer» C. Hysteresis loss | |
41. |
_Permanent magnets are normally made of$? |
A. | Alnico alloys |
B. | Aluminium |
C. | Cast iron |
D. | Wrought iron |
Answer» B. Aluminium | |
42. |
_If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be$? |
A. | Zero |
B. | Small |
C. | Large |
D. | None of the above |
Answer» D. None of the above | |
43. |
_Relative permeability of vacuum is$? |
A. | 1 |
B. | 1 H/m |
C. | 1/4JI |
D. | 4n √ó 10' H/m |
Answer» B. 1 H/m | |
44. |
_The unit of magnetic flux is$? |
A. | Henry |
B. | Weber |
C. | Ampere-turn/weber |
D. | Ampere/metre |
Answer» C. Ampere-turn/weber | |
45. |
The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is ___________Vs$? |
A. | 50 |
B. | 20 |
C. | 0.05 |
D. | 500 |
Answer» C. 0.05 | |
46. |
Conductance is analogous to$? |
A. | Permeance |
B. | Reluctance |
C. | Flux |
D. | Inductance |
Answer» B. Reluctance | |
47. |
Silicon steel is used in electrical machines because it has$? |
A. | Low coercivity |
B. | Low retentivity |
C. | Low hysteresis loss |
D. | High coercivity |
Answer» D. High coercivity | |
48. |
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 |
Answer» B. Increases their cost of manufacture | |
49. |
Conductance is analogous to? |
A. | Permeance |
B. | Reluctance |
C. | Flux |
D. | Inductance |
Answer» B. Reluctance | |
50. |
Silicon steel is used in electrical machines because it has? |
A. | Low coercivity |
B. | Low retentivity |
C. | Low hysteresis loss |
D. | High coercivity |
Answer» D. High coercivity | |