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Friday, 23 October 2015

Magnetism and Electromagnetism - Multiple Choice Questions

Magnetism and Electromagnetism - Multiple Choice Questions Points : magnetism and electromagnetism multiple choice questions and answers, electrical objective type question answers, mcqs 1. Magnetic flux density is a
(i) vector quantity
(ii) scalar quantity
(iii) phasor
(iv) none of above

2. The major advantage of impermanent magnets is that we can
(i) change the magnetic flux
(ii) use any magnetic material
(iii) decrease the hysteresis loss
(iv) none of above

3. Magnetic material use in stable magnets is
(i) iron
(ii) soft steel
(iii) nickel
(iv) hardened steel

4. One weber is able to
(i) 102 lines
(ii) 4π x 10-7 Lines
(iii) 1012 lines
(iv) 108 lines

5. When relative permeability of a material is a little less than I, It is call a
(i) diamagnetic material
(ii) paramagnetic material
(iii) ferromagnetic material
(iv) none of the above

6. When magnet is intense
(i) it gains magnetism
(ii) it loses magnetism
(iii) it neither loses nor gins magnetism
(iv) none of the above

7. When relative permeability of material is greatly greater than 1, it is called
(i) diamagnetic material
(ii) paramagnetic material
(iii) ferromagnetic material
(iv) none of above

8. Magnetic field intensity is a
(i) scalar quantity
(ii) vector quantity
(iii) phasor
(iv) none of the above

9. Which of following is added proper for core of an electromagnet
(i) soft iron
(ii) air
(iii) steel
(iv) tungsten steel

10. Magnetic material use in impermanent magnets is
(i) hardened steel
(ii) cobalt steel
(iii) soft iron
(iv) tungsten steel

10. Source of a magnetic field is
(i) an isolated magnetic pole
(ii) static electric charge
(iii) magnetic substances
(iv) current loop

12. Greater percentage of substances are
(i) diamagnetic
(ii) paramagnetic
(iii) ferromagnetic
(iv) none of the above

13. Unit of pole force is
(i) A/m2
(ii) Am
(iii) Am2
(iv) Wb/m2

14. Magnetic needle is kept in a regular magnetic field. It experience
(i) a force and a torque
(ii) a force but not a torque
(iii) a torque but not a force
(iv) neither a torque nor a force

15. AT/m is the unit of
(i) m.m.f.
(ii) reluctance
(iii) magnetizing force
(iv) magnetic flux density

16. When relative permeability of a material is slightly more than I. it is call a
(i) diamagnetic material
(ii) paramagnetic material
(iii) ferromagnetic material
(iv) none of the above

17. Magnetic flux pass more readily through
(i) air
(ii) wood
(iii) vacuum
(iv) iron

18. Magnet is kept in air surrounded through an iron ring. The magnetic lines of force as of the magnet will be
(i) crowded in the ring
(ii) crowded in air
(iii) evenly distributed
(iv) none of the above

19. Iron is ferromagnetic
(i) above 770°C
(ii) below 770°C
(iii) at all temperatures
(iv) none of the above

20. Magnetic needle is kept in a non-uniform magnetic field. It experiences
(i) a force and a torque
(ii) a force but not a torque
(iii) a torque but not a force
(iv) neither a force nor a torque

21. Relative permeability of a material is 0.9998. it is
(i) diamagnetic
(ii) paramagnetic
(iii) ferromagnetic
(iv) none of the above

22. Demagnetising of magnets can be done through
(i) rough handling
(ii) heating
(iii) magnetizing in opposite direction
(iv) all of the above

23. Relative permeability of iron is of order of
(i) zero
(ii) 104
(iii) 1
(iv) 10

24. Magnetic field is cause by
(i) stationary charge
(ii) a moving positive charge only
(iii) a moving negative charge only
(iv) moving positive and negative charges both

25. Charged particle enter a magnetic field perpendicular to magnetic lines of force. The path of the particle is
(i) straight line
(ii) circular
(iii) ellipse
(iv) spiral

26. Through rising number of turns 3 times in a toroid, the magnetic flux
(i) will remain unchanged
(ii) will become three times
(iii) will reduce to one-third
(iv) none of the above

27. Which of following has the uppermost permeability?
(i) paramagnetic
(ii) diamagnetic
(iii) ferromagnetic
(iv) vacuum

28. Magnetic lines of force
(i) intersect at infinity
(ii) intersect within the magnet
(iii) cannot intersect at all
(iv) none of the above

29. Unit of relative permeability is
(i) A/m
(ii) H/m
(iii) Wb/m2
(iv) none of the above

30. Distance among two magnetic poles is double and their pole strength are too doubled. The force among them
(i) increases four times
(ii) decreases four times
(iii) remains unchanged
(iv) none of the above

31. When a charged particle move through a magnetic field, it suffer a change in
(i) direction
(ii) speed
(iii) energy
(iv) no change

32. Current is accepted through a straight wire. Magnetic field established about it has magnetic lines of force
(i) circular and endless
(ii) straight
(iii) oval in shape and endless
(iv) none of the above

33. Charged particle enter a magnetic field at an angle of 30° to direction of magnetic field. Its pathway becomes
(i)) circular
(ii) straight line
(iii) elliptical
(iv) helical

34. An electron is travelling horizontally towards east. Magnetic field in vertically downward direction exert a force on electron along
(i) north
(ii) south
(iii) east
(iv) west

35. Deflection in a galvanometer fails as of 50 divisions to 20 divisions while a 12 Ω shunt is apply. Galvanometer resistance is
(i) 18Ω
(ii) 6Ω
(iii) 9Ω
(iv) 24Ω

36. Magnetic field in a moving coil galvanometer finished radial to
(i) make the field stronger
(ii) make the field weaker
(iii) make the scale linear
(iv) to reduce its resistance

37. Magnetic field inside a current moving solenoid is
(i) directly proportional to current
(ii) directly proportional to its length
(iii) inversely proportional to number of turns
(iv) inversely proportional to current

38. Strong magnetic field is applied on stationary electron. Then electron
(i) remains stationary
(ii) starts spinning
(iii) moves in the direction of field.
(iv) moves in an opposite direction

39. An electron moves by a regular velocity v and enters a region of regular magnetic field B. If v and B are parallel to each other then electron will
(i) move in a circular path
(ii) move in a direction perpendicular to B.
(iii) continue to moves in the same direction
(iv) not move at all

40. To send 10% of the major current through a galvanometer of resistance 99Ω , value of shunt resistance required is
(i) 11Ω
(ii) 33Ω
(iii) 9.9Ω
(iv) 22Ω

41. Strong magnetic field is applied to a motionless electron. Then the electron
(i) moves in the direction of field
(ii) moves in an opposite direction
(iii) remains stationary
(iv) starts spinning

42. Moving electric charge will generate
(i) electric field only
(ii) both electric and magnetic fields
(iii) magnetic field only
(iv) no field

43. The resistance of an ideal voltmeter is
(i) zero
(ii) infinite
(iii) very low
(iv) data incomplete

44. Ammeter of range 1A has a resistance of 0.9Ω. To expand range to 10A, value of shunt necessary is
(i) 0.9Ω
(ii) 0.3Ω
(iii) 0.01Ω
(iv) 0.1Ω

45. If an electron enters a consistent magnetic field obliquely, path of electron will become
(i) an ellipse
(ii) a circle
(iii) a spiral
(iv) none of above

46. Current in a wire is directed towards east and wire is sited in a magnetic field directed toward north. Force on the wire is
(i) due east
(ii) due south
(iii) vertically downward
(iv) vertically upward

47. Current flows in a conductor as of east to west. Direction of magnetic field at a point above the conductor is
(i) toward north
(ii) toward south
(iii) toward east
(iv) toward west

48. Charged particle moves through a magnetic field perpendicular to it. Energy of particle will
(i) decrease
(ii) increase
(iii) remain unchanged
(iv) become zero

49. In exceeding question, the momentum of particle will
(i) be zero
(ii) change
(iii) not change
(iv) none of above

50. Direct current is sent through a helical spring. Spring tends
(i) to get shorter
(ii) to rotate about the axis
(iii) to get longer
(iv) to move eastward

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