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magnetism and electromagnetism MCQs

Practise focused magnetism and electromagnetism questions with marked answers for exam preparation and subject revision.

magnetism and electromagnetism Mcqs
1. Ferrites are materials
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A. diamagnetic

B. none of the above

C. paramagnetic

D. ferromagnetic
2. The bar magnet has____________?
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A. monopole moment

B. the dipole moment

C. none of the above

D. A. and B. both

3. Which of the following is a vector quantity ?
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A. Flux density

B. Magnetic potential

C. Magnetic field intensity

D. Relative permeability

4. Tesla is a unit of_____________?
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A. flux density

B. flux

C. field strength

D. inductance

5. The materials having low retentivity are suitable for making_____________?
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A. temporary magnets

B. weak magnets

C. none of the above

D. permanent magnets

6. A magnetic field exists around____________?
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A. copper

B. iron

C. aluminium

D. moving charges
7. In a simple magnetic field the strength of magnet flux_______________?
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A. is constant and has same value in energy part of the magnetic field

B. increases continuously from initial value to final value

C. first increases and then decreases till it becomes zero

D. decreases continuously from initial value to final value

8. What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200 ?
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A. 4

B. 6

C. 2

D. 8

9. The materials are a bit inferior conductors of magnetic flux than air
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A. paramagnetic

B. diamagnetic

C. dielectric

D. ferromagnetic

10. A permanent magnet______________?
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A. attracts only ferromagnetic substances

B. attracts ferromagnetic substances and repels all others

C. attracts all paramagnetic substances and repels others

D. attracts some substances and repels others
11. 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 ?
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A. 63.38 N/Wb

B. 633.8 N/Wb

C. 63380 N/Wb

D. 6338 N/Wb
12. Reciprocal of permeability is____________?
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A. permittivity

B. susceptibility

C. reluctivity

D. conductance

13. 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______________?
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A. BLI2

B. BLI

C. zero

D. B2LI

14. Which of the following is the unit of magnetic flux density ?
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A. tesla

B. none of the above

C. weber

D. lumens

15. The change of cross-sectional area of conductor in magnetic field will affect______________?
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A. reluctance of conductor

B. resistance of conductor

C. A. and B. both in the same way

D. none of the above

16. The attraction capacity of electromagnet will increase if the_______________?
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A. flux density decreases

B. flux density increases

C. core length increases i

D. core area increases

17. A permeable substance is one_____________?
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A. which is a good conductor

B. through which the magnetic lines of force can pass very easily

C. which is a strong magnet

D. which is a bad conductor

18. When an iron piece is placed in a magnetic field_____________?
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A. the magnetic field will not be affected

B. the magnetic lines of force will bend away from their usual paths in order to go away from the piece

C. the magnetic lines of force will bend away from their usual paths in order to pass through the piece

D. the iron piece will break

19. Magnetism of a magnet can be destroyed by_____________?
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A. hammering

B. by inductive action of another magnet

C. heating

D. by all above methods
20. The magneto-motive force is______________?
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A. the voltage across the two ends of exciting coil

B. the passage of magnetic field through an exciting coil

C. the sum of all currents embraced by one line of magnetic field

D. the flow of an electric current

21. Susceptibility is positive for______________?
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A. diamagnetic substances

B. none of the above

C. non-magnetic substances

D. ferromagnetic substances
22. Materials subjected to rapid reversal of magnetism should have______________?
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A. high co-ercivity and high retentivity

B. high co-ercivity and low density

C. large area oiB-H loop

D. high permeability and low hysteresis loss
23. Unit for quantity of electricity is_____________?
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A. joule

B. watt

C. ampere-hour

D. coulomb
24. The relative permeability of materials is not constant
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A. diamagnetic

B. insulating

C. ferromagnetic

D. paramagnetic

25. 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______________?
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A. a plastic shielding is provided

B. meter is surrounded by strong magnetic fields

C. a soft iron shielding is used

D. a shielding of anon-magnetic material is used

26. Magnetic moment is a_____________?
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A. vector quantity

B. scalar quantity

C. universal constant

D. pole strength

27. The direction of magnetic lines of force is________________?
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A. from one end of the magnet to another

B. none of the above

C. from south pole to north pole

D. from north pole to south pole
28. A material which is slightly repelled by a magnetic field is known as_____________?
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A. paramagnetic material

B. diamagnetic material

C. conducting material

D. ferromagnetic material

29. 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 ?
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A. Decreases

B. Increases

C. Remains same

D. First increases and then decreases depending on the depth of iron insertion

30. How does the magnetic compass needle behave in a magnetic field ?
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A. None of the above

B. It assures a position which follows a line of magnetic flux

C. It assures a position right angle to magnetic field

D. It starts rotating

31. The ratio of intensity of magnetisation to the magnetisation force is known as_____________?
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A. none of the above

B. susceptibility

C. relative permeability

D. flux density

32. The stray line of magnetic flux is defined as_____________?
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A. a line of magnetic flux in a non-uniform field

B. a line of magnetic flux which does not follow the designed path

C. a line vertical to the flux lines

D. the mean length of a ring shaped coil

33. The relative permeability is less than unity is case of_____________?
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A. ferrites

B. non-ferrous materials

C. ferromagnetic materials

D. diamagnetic materials
34. In the left hand rule, forefinger always represents______________?
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A. direction of force on the conductor

B. voltage

C. current

D. magnetic field
35. Which of the following is not a unit of flux?
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A. Telsa

B. All of the above

C. Maxwell

D. Weber

36. The initial permeability of an iron rod is________________?
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A. the permeability at the end of the iron rod

B. the lowest permeability of the iron rod

C. the permeability almost in non-magnetised state

D. the highest permeability of the iron rod

37. One telsa is equal to___________?
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A. 1 Wb/m2

B. 1 Wb/mm2

C. 1 Wb/m

D. 1 mWb/m2

38. Two infinitely long parallel conductors in vacuum any separated 1 metre between centers >then a current of 1 ampere flows the. uk each conductor, produce on each other a force of_________________?
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A. 2 x KT3 N/m

B. 2 x 1(T2 N/m)

C. 2x 1(T7 N/m)

D. 2 x 10?5 N/m

39. he retentivity (a property) of material is useful for the construction of__________?
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A. electromagnets

B. transformers

C. non-magnetic substances

D. permanent magnets
40. For which of the following materials the saturation value is the highest ?
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A. Ferromagnetic materials

B. Paramagnetic materials

C. Ferrites

D. Diamagnetic materials

41. The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is________________?
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A. proportional to 7

B. proportional to distance between the conductors

C. inversely proportional to I

D. proportional to X
42. Gilbert is a unit of_______________?
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A. electromotive force

B. permittivity

C. conductance

D. magnetomotive force
43. Which of the following type of materials are not very important for engineering applications ?
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A. None of the above

B. Diamagnetic

C. Ferromagnetic

D. Paramagnetic

44. A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be______________?
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A. M/4

B. M/2

C. 2 M

D. M

45. Out of the following statements, concerning an electric field, which statement is not true ?
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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. Unit field intensity in the exertion of a force of one newton on a charge of one coulomb

D. An electric field is defined as a point in space at which an electric charge would experience a force

46. Substances which have permeability less than the permeability of free space are known as_____________?
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A. paramagnetic

B. ferromagnetic

C. bipolar

D. diamagnetic
47. Temporary magnets are used in______________?
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A. loud-speakers

B. all of the above

C. motors

D. generators

48. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be_____________?
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A. 1 N

B. 10 N

C. 0.1 N

D. 100 N

49. Air gap has_________eluctance as compared to iron or steel path?
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A. little

B. lower

C. zero

D. higher

50. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity?
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A. equal to that of disc and in the same direction

B. less than 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 but in opposite direction