McqMate
Chapters
| 1. |
Tesla is a unit of |
| A. | field strength |
| B. | inductance |
| C. | flux density |
| D. | flux |
| Answer» C. flux density | |
| 2. |
A permeable substance is one |
| A. | which is a good conductor |
| B. | which is a bad conductor |
| C. | which is a strong magnet |
| D. | through which the magnetic lines of force can pass very easily |
| Answer» D. through which the magnetic lines of force can pass very easily | |
| 3. |
The materials having low retentivity are suitable for making |
| A. | weak magnets |
| B. | temporary magnets |
| C. | permanent magnets |
| D. | none of the above |
| Answer» B. temporary magnets | |
| 4. |
A magnetic field exists around |
| A. | iron |
| B. | copper |
| C. | aluminium |
| D. | moving charges |
| Answer» D. moving charges | |
| 5. |
Ferrites are materials. |
| A. | paramagnetic |
| B. | diamagnetic |
| C. | ferromagnetic |
| D. | none of the above |
| Answer» C. ferromagnetic | |
| 6. |
Air gap has_______eluctance as compared to iron or steel path |
| A. | little |
| B. | lower |
| C. | higher |
| D. | zero |
| Answer» B. lower | |
| 7. |
The direction of magnetic lines of force is |
| A. | from south pole to north pole |
| B. | from north pole to south pole |
| C. | from one end of the magnet to another |
| D. | none of the above |
| Answer» B. from north pole to south pole | |
| 8. |
Which of the following is a vector quantity ? |
| A. | Relative permeability |
| B. | Magnetic field intensity |
| C. | Flux density |
| D. | Magnetic potential |
| Answer» B. Magnetic field intensity | |
| 9. |
The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is |
| A. | proportional to 7 |
| B. | proportional to X |
| C. | proportional to distance between the conductors |
| D. | inversely proportional to I |
| Answer» B. proportional to X | |
| 10. |
A material which is slightly repelled by a magnetic field is known as |
| A. | ferromagnetic material |
| B. | diamagnetic material |
| C. | paramag>etic material |
| D. | conducting material |
| Answer» B. diamagnetic material | |
| 11. |
When an iron piece is placed in a magnetic field |
| A. | the magnetic lines of force will bend away from their usual paths in order to go away from the piece |
| B. | the magnetic lines of force will bend away from their usual paths in order to pass through the piece |
| C. | the magnetic field will not be affected |
| D. | the iron piece will break |
| Answer» B. the magnetic lines of force will bend away from their usual paths in order to pass through the piece | |
| 12. |
Fleming's left hand rule is used to find |
| A. | direction of magnetic field due to current carrying conductor |
| B. | direction of flux in a solenoid |
| C. | direction of force on a current car¬rying conductor in a magnetic field |
| D. | polarity of a magnetic pole |
| Answer» C. direction of force on a current car¬rying conductor in a magnetic field | |
| 13. |
The ratio of intensity of magnetisation to the magnetisation force is known as |
| A. | flux density |
| B. | susceptibility |
| C. | relative permeability |
| D. | none of the above |
| Answer» B. susceptibility | |
| 14. |
Magnetising steel is normals difficult because |
| A. | it corrodes easily |
| B. | it has high permeability |
| C. | it has high specific gravity |
| D. | it has low permeability |
| Answer» D. it has low permeability | |
| 15. |
The left hand rule correlates to |
| A. | current, induced e.m.f. and direc¬tion of force on a conductor |
| B. | magnetic field, electric field and direction of force on a conductor |
| C. | self induction, mutual induction and direction of force on a conductor |
| D. | current, magnetic field and direc¬tion of force on a conductor |
| Answer» D. current, magnetic field and direc¬tion of force on a conductor | |
| 16. |
The unit of relative permeability is |
| A. | henry/metre |
| B. | henry |
| C. | henry/sq. m |
| D. | it is dimensionless |
| Answer» D. it is dimensionless | |
| 17. |
A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be |
| A. | zero |
| B. | BLI |
| C. | B2LI |
| D. | BLI2 |
| Answer» A. zero | |
| 18. |
The force between two long parallel conductors is inversely proportional to |
| A. | radius of conductors |
| B. | current in one conductor |
| C. | product of current in two conduc¬tors |
| D. | distance between the conductors |
| Answer» D. distance between the conductors | |
| 19. |
Materials subjected to rapid reversal of magnetism should have |
| A. | large area oiB-H loop |
| B. | high permeability and low hysteresis loss |
| C. | high co-ercivity and high reten-tivity |
| D. | high co-ercivity and low density |
| Answer» B. high permeability and low hysteresis loss | |
| 20. |
Indicate which of the following material does not retain magnetism permanently. |
| A. | Soft iron |
| B. | Stainless steel |
| C. | Hardened steel |
| D. | None of the above |
| Answer» A. Soft iron | |
| 21. |
The main constituent of permalloy is |
| A. | cobalt |
| B. | chromium |
| C. | nickel |
| D. | tungsten |
| Answer» C. nickel | |
| 22. |
The use of permanent magnets is. not made in |
| A. | magnetoes |
| B. | energy meters |
| C. | transformers |
| D. | loud-speakers |
| Answer» C. transformers | |
| 23. |
Paramagnetic materials have relative permeability |
| A. | slightly less than uuity |
| B. | equal to unity |
| C. | slightly more than unity |
| D. | equal to that ferromagnetic mate rials |
| Answer» C. slightly more than unity | |
| 24. |
Substances which have permeability less than the permeability of free space are known as |
| A. | ferromagnetic |
| B. | paramagnetic |
| C. | diamagnetic |
| D. | bipolar |
| Answer» C. diamagnetic | |
| 25. |
Two infinitely long parallel conductors in vacuum anf' separated 1 metre between centres >rhen a current of 1 ampere flows thn. ugh each conductor, produce on each otLer a force of |
| A. | 2 x 1(T2 N/m) |
| B. | 2 x KT3 N/m |
| C. | 2 x 10"5 N/m |
| D. | 2x 1(T7 N/m) |
| Answer» D. 2x 1(T7 N/m) | |
| 26. |
In the left hand rule, forefinger always represents |
| A. | voltage |
| B. | current |
| C. | magnetic field |
| D. | direction of force on the conductor |
| Answer» C. magnetic field | |
| 27. |
Which of the following is a ferromagnetic material ? |
| A. | Tungsten |
| B. | Aluminium |
| C. | Copper |
| D. | Nickel |
| Answer» D. Nickel | |
| 28. |
Ferrites are a sub-group of |
| A. | non-magnetic materials |
| B. | ferro-magnetic materials |
| C. | paramagnetic materials |
| D. | ferri-magnetic materials |
| Answer» D. ferri-magnetic materials | |
| 29. |
Gilbert is a unit of |
| A. | electromotive force |
| B. | magnetomotive force |
| C. | conductance |
| D. | permittivity |
| Answer» B. magnetomotive force | |
| 30. |
The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields |
| A. | meter is surrounded by strong magnetic fields |
| B. | a soft iron shielding is used |
| C. | a plastic shielding is provided |
| D. | a shielding of anon-magnetic material is used |
| Answer» B. a soft iron shielding is used | |
| 31. |
Reciprocal of permeability is |
| A. | reluctivity |
| B. | susceptibility |
| C. | permittivity |
| D. | conductance |
| Answer» A. reluctivity | |
| 32. |
The relative permeability is less than unity is case of |
| A. | ferromagnetic materials |
| B. | ferrites |
| C. | non-ferrous materials |
| D. | diamagnetic materials |
| Answer» D. diamagnetic materials | |
| 33. |
Which of the following is the unit of magnetic flux density ? |
| A. | weber |
| B. | lumens |
| C. | tesla |
| D. | none of the above |
| Answer» C. tesla | |
| 34. |
The magnetism left in the iron after exciting field has been removed is known as |
| A. | permeance |
| B. | residual magnetism |
| C. | susceptance |
| D. | reluctance |
| Answer» B. residual magnetism | |
| 35. |
Which of the following is not a unit of flux? |
| A. | Maxwell |
| B. | Telsa |
| C. | Weber |
| D. | All of the above |
| Answer» B. Telsa | |
| 36. |
Which of the following is expected to have the maximum permeability ? |
| A. | Brass |
| B. | Copper |
| C. | Zinc |
| D. | Ebonite |
| Answer» D. Ebonite | |
| 37. |
One telsa is equal to |
| A. | 1 Wb/mm2 |
| B. | 1 Wb/m |
| C. | 1 Wb/m2 |
| D. | 1 mWb/m2 |
| Answer» C. 1 Wb/m2 | |
| 38. |
Out of the following statements, concerning an electric field, which statement is not true ? |
| A. | The electric intensity is a vector quantity |
| B. | The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point |
| C. | An electric field is defined as a point in space at which an electric charge would experienc* a force |
| D. | Unit field intensity in the exertion of a force of one newton on a charge of one coulomb |
| Answer» B. The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point | |
| 39. |
When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon |
| A. | resistance of the coil |
| B. | motion of the magnet |
| C. | number of turns of the coil |
| D. | pole strength of the magnet |
| Answer» A. resistance of the coil | |
| 40. |
One maxwell is equal to |
| A. | 10 webers |
| B. | 10 webers |
| C. | 10 webers |
| D. | 10 webers |
| Answer» D. 10 webers | |
| 41. |
When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the centre of the circle |
| A. | will be zero |
| B. | will be infinite |
| C. | will depend on the amount of e.m.f. applied |
| D. | will depend on the radius of the circle |
| Answer» D. will depend on the radius of the circle | |
| 42. |
Susceptibility is positive for |
| A. | non-magnetic substances |
| B. | diamagnetic substances |
| C. | ferromagnetic substances |
| D. | none of the above |
| Answer» C. ferromagnetic substances | |
| 43. |
Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per metre of length of each conductor will be |
| A. | 100 N |
| B. | 10 N |
| C. | 1 N |
| D. | 0.1 N |
| Answer» D. 0.1 N | |
| 44. |
A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be |
| A. | 240 N |
| B. | 24 N |
| C. | 2.4 N |
| D. | 0.24 N |
| Answer» C. 2.4 N | |
| 45. |
The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength ? |
| A. | 2500 AT/m |
| B. | 250 AT/m |
| C. | 25 AT/m |
| D. | 2.5 AT/m |
| Answer» B. 250 AT/m | |
| 46. |
What is the magnitude and the direction of force per 1.1m length of a pair of conductors of a direct current linecarrying 10 amperes and spaced 100 mm apart ? |
| A. | 22 x 10"8 N |
| B. | 22 x 10"7 N |
| C. | 22 x 10-6 N |
| D. | 22 x 10"5 N |
| Answer» D. 22 x 10"5 N | |
| 47. |
A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ? |
| A. | 63.38 N/Wb |
| B. | 633.8 N/Wb |
| C. | 6338 N/Wb |
| D. | 63380 N/Wb |
| Answer» C. 6338 N/Wb | |
| 48. |
The unit of flux is the same as that of |
| A. | reluctance |
| B. | resistance |
| C. | permeance |
| D. | pole strength |
| Answer» D. pole strength | |
| 49. |
Unit for quantity of electricity is |
| A. | ampere-hour |
| B. | watt |
| C. | joule |
| D. | coulomb |
| Answer» D. coulomb | |
| 50. |
The Biot-savart's law is a general modification of |
| A. | Kirchhoffs law |
| B. | Lenz's law |
| C. | Ampere's law |
| D. | Faraday's laws |
| Answer» C. Ampere's law | |
| 51. |
The most effective and quickest may of making a magnet from soft iron is by |
| A. | placing it inside a coil carrying current |
| B. | induction |
| C. | the use of permanent magnet |
| D. | rubbing with another magnet |
| Answer» A. placing it inside a coil carrying current | |
| 52. |
The commonly used material for shielding or screening magnetism is |
| A. | copper |
| B. | aluminium |
| C. | soft iron |
| D. | brass |
| Answer» C. soft iron | |
| 53. |
If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity |
| A. | less than that of disc but in opposite direction |
| B. | equal to that of disc and in the same direction |
| C. | equal to that of disc and in the opposite direction |
| D. | less than that of disc and in the same direction |
| Answer» D. less than that of disc and in the same direction | |
| 54. |
A permanent magnet |
| A. | attracts some substances and repels others |
| B. | attracts all paramagnetic substan¬ces and repels others |
| C. | attracts only ferromagnetic sub¬stances |
| D. | attracts ferromagnetic substances and repels all others |
| Answer» A. attracts some substances and repels others | |
| 55. |
The retentivity (a property) of material is useful for the construction of |
| A. | permanent magnets |
| B. | transformers |
| C. | non-magnetic substances |
| D. | electromagnets |
| Answer» A. permanent magnets | |
| 56. |
The relative permeability of materials is not constant. |
| A. | diamagnetic |
| B. | paramagnetic |
| C. | ferromagnetic |
| D. | insulating |
| Answer» C. ferromagnetic | |
| 57. |
The materials are a bit inferior conductors of magnetic flux than air. |
| A. | ferromagnetic |
| B. | paramagnetic |
| C. | diamagnetic |
| D. | dielectric |
| Answer» C. diamagnetic | |
| 58. |
Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials. |
| A. | circular |
| B. | triangular |
| C. | rectangular |
| D. | none of the above |
| Answer» C. rectangular | |
| 59. |
A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be |
| A. | M |
| B. | M/2 |
| C. | 2 M |
| D. | M/4 |
| Answer» B. M/2 | |
| 60. |
A keeper is used to |
| A. | change the direction of magnetic lines |
| B. | amplify flux |
| C. | restore lost flux |
| D. | provide a closed path for flux |
| Answer» D. provide a closed path for flux | |
| 61. |
Magnetic moment is a |
| A. | pole strength |
| B. | universal constant |
| C. | scalar quantity |
| D. | vector quantity |
| Answer» D. vector quantity | |
| 62. |
The change of cross-sectional area of conductor in magnetic field will affect |
| A. | reluctance of conductor |
| B. | resistance of conductor |
| C. | (a) and (b) b >th in the same way |
| D. | none of the above |
| Answer» C. (a) and (b) b >th in the same way | |
| 63. |
The uniform magnetic field is |
| A. | the field of a set of parallel conductors |
| B. | the field of a single conductor |
| C. | the field in which all lines of mag¬netic flux are parallel and equidis¬tant |
| D. | none of the above |
| Answer» C. the field in which all lines of mag¬netic flux are parallel and equidis¬tant | |
| 64. |
The magneto-motive force is |
| A. | the voltage across the two ends of exciting coil |
| B. | the flow of an electric current |
| C. | the sum of all currents embraced by one line of magnetic field |
| D. | the passage of magnetic field through an exciting coil |
| Answer» C. the sum of all currents embraced by one line of magnetic field | |
| 65. |
What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200 ? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» B. 4 | |
| 66. |
What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m ? |
| A. | 2 AT |
| B. | 4 AT |
| C. | 6 AT |
| D. | 10 AT |
| Answer» B. 4 AT | |
| 67. |
A certain amount of current flows through a ring-shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil ? |
| A. | Decreases |
| B. | Increases |
| C. | Remains same |
| D. | First increases and then decreases depending on the depth of iron in¬sertion |
| Answer» B. Increases | |
| 68. |
The magnetic reluctance of a material |
| A. | decreases with increasing cross sectional area of material |
| B. | increases with increasing cross-sec-tional area of material |
| C. | does not vary with increasing cross-sectional area of material |
| D. | any of the above |
| Answer» A. decreases with increasing cross sectional area of material | |
| 69. |
The initial permeability of an iron rod is |
| A. | the highest permeability of the iron rod |
| B. | the lowest permeability of the iron rod |
| C. | the permeability at the end of the iron rod |
| D. | the permeability almost in non-magnetised state |
| Answer» D. the permeability almost in non-magnetised state | |
| 70. |
How does the magnetic compass needle behave in a magnetic field ? |
| A. | It assures a position right angle to magnetic field |
| B. | It starts rotating |
| C. | It assures a position which follows a line of magnetic flux |
| D. | None of the above |
| Answer» C. It assures a position which follows a line of magnetic flux | |
| 71. |
In a simple magnetic field the strength of magnet flux |
| A. | is constant and has same value in energy part of the magnetic field |
| B. | increases continuously from initial value to final value |
| C. | decreases continuously from initial value to final value |
| D. | first increases and then decreases till it becomes zero |
| Answer» D. first increases and then decreases till it becomes zero | |
| 72. |
The stray line of magnetic flux is defined as |
| A. | a line vertical to the flux lines |
| B. | the mean length of a ring shaped coil |
| C. | a line of magnetic flux in a non-uniform field |
| D. | a line of magnetic flux which does not follow the designed path |
| Answer» D. a line of magnetic flux which does not follow the designed path | |
| 73. |
The bar magnet has |
| A. | the dipole moment |
| B. | monopole moment |
| C. | (a) and (b) both |
| D. | none of the above |
| Answer» A. the dipole moment | |
| 74. |
Which of the following materials are dia-magnetic ? |
| A. | Silver |
| B. | Copper |
| C. | Silver and copper |
| D. | Iron |
| Answer» C. Silver and copper | |
| 75. |
Which of the following type of materials are not very important for engineering applications ? |
| A. | Ferromagnetic |
| B. | Paramagnetic |
| C. | Diamagnetic |
| D. | None of the above |
| Answer» C. Diamagnetic | |
| 76. |
The susceptibility of paramagnetic materials generally lies between |
| A. | KT3 and 1CT6 |
| B. | 1CT3 and 1CT7 |
| C. | KT4 and KT8 |
| D. | 10"2 and KT5 |
| Answer» A. KT3 and 1CT6 | |
| 77. |
For which of the following materials the saturation value is the highest ? |
| A. | Ferromagnetic materials |
| B. | Paramagnetic materials |
| C. | Diamagnetic materials |
| D. | Ferrites |
| Answer» D. Ferrites | |
| 78. |
The magnetic materials exhibit the property of magnetisation because of |
| A. | orbital motion of electrons |
| B. | spin of electrons |
| C. | spin of nucleus |
| D. | either of these |
| Answer» C. spin of nucleus | |
| 79. |
For which of the following materials the net magnetic moment should be zero ? |
| A. | Diamagnetic materials |
| B. | Ferrimagnetic materials |
| C. | Antiferromagnetic materials |
| D. | Antiferrimagnetic materials |
| Answer» C. Antiferromagnetic materials | |
| 80. |
The attraction capacity of electromagnet will increase if the |
| A. | core length increases i |
| B. | core area increases |
| C. | flux density decreases |
| D. | flux density increases |
| Answer» D. flux density increases | |
| 81. |
Which of the following statements is correct ? |
| A. | The conductivity of ferrites is better than ferromagnetic materials |
| B. | The conductivity of ferromagnetic materials is better than ferrites |
| C. | The conductivity of ferrites is very high |
| D. | The conductivity of ferrites is same as that of ferromagnetic materials |
| Answer» A. The conductivity of ferrites is better than ferromagnetic materials | |
| 82. |
Temporary magnets are used in |
| A. | loud-speakers |
| B. | generators |
| C. | motors |
| D. | all of the above |
| Answer» D. all of the above | |
| 83. |
Main causes of noisy solenoid are |
| A. | strong tendency of fan out of lami-nations at the end caused by repul¬sion among magnetic lines of force |
| B. | uneven bearing surface, caused by dirt or uneven wear between moving and stationary parts |
| C. | both of above |
| D. | none of the above |
| Answer» C. both of above | |
| 84. |
Core of an electromagnet should have |
| A. | low coercivity |
| B. | high susceptibility |
| C. | both of the above |
| D. | none of the above |
| Answer» C. both of the above | |
| 85. |
Magnetism of a magnet can be destroyed by |
| A. | heating |
| B. | hammering |
| C. | by inductive action of another magnet |
| D. | by all above methods |
| Answer» D. by all above methods | |
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