1. A magnetic field exists around
(a) iron
(b) copper
(c) aluminium
(d) moving charges
Ans: d
2. Which of the following is a vector quantity ?
(a) Relative permeability
(b) Magnetic field intensity
(c) Flux density
(d) Magnetic potential
Ans: b
3. 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
Ans: b
4. 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
Ans: d
5. The unit of relative permeability is
(a) henry/metre
(b) henry
(c) henry/sq. m
(d) it is dimensionless
Ans: d
6. The main constituent of permalloy is
(a) cobalt
(b) chromium
(c) nickel
(d) tungsten
Ans: c
7. Degaussing is the process of
(a) removal of magnetic impurities
(b) removing gases from the materials
(c) remagnetising metallic parts
(d) demagnetising metallic parts
Ans: d
8. Ferrites are a sub-group of
(a) non-magnetic materials
(b) ferro-magnetic materials
(c) paramagnetic materials
(d) ferri-magnetic materials
Ans: d
9. Gilbert is a unit of
(a) electromotive force
(b) magnetomotive force
(c) conductance
(d) permittivity
Ans: b
10. 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
Ans: b
11. Reciprocal of permeability is
(a) reluctivity
(b) susceptibility
(c) permittivity
(d) conductance
Ans: a
12. Which of the following is expected to have the maximum permeability ?
(a) Brass
(b) Copper
(c) Zinc
(d) Ebonite
Ans: d
13. 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 experience a force
(d) Unit field intensity in the exertion of a force of one newton on a charge of one coulomb
Ans: b
14. The unit of flux is the same as that of
(a) reluctance
(b) resistance
(c) permeance
(d) pole strength
Ans: d
15. 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
Ans: c
16. The commonly used material for shielding or screening magnetism is
(a) copper
(b) aluminium
(c) soft iron
(d) brass
Ans: c
17. A permanent magnet
(a) attracts some substances and repels others
(b) attracts all paramagnetic substances and repels others
(c) attracts only ferromagnetic substances
(d) attracts ferromagnetic substances and repels all others
Ans: a
18. 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
Ans: d
19. Magnetic moment is a
(a) pole strength
(b) universal constant
(c) scalar quantity
(d) vector quantity
Ans: d
20. Which of the following statements is correct ?
(a) The magnetic flux inside an exciting coil is lower than its outside surface
(b) The magnetic flux inside an exciting coil is zero
(c) The magnetic flux inside the exciting coil is greater than its outside surface
(d) The magnetic flux inside the exciting coil is same as on its outside surface
Ans: d
21. 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
Ans: d
22. 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
Ans: c
23. The bar magnet has
(a) the dipole moment
(b) monopole moment
(c) (a) and (b) both
(d) none of the above
Ans: a
24. 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
Ans: c
25. For which of the following materials the saturation value is the highest ?
(a) Ferromagnetic materials
(b) Paramagnetic materials
(c) Diamagnetic materials
(d) Ferrites
Ans: d
26. 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
(e) all of the above
Ans: c
27. 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
Ans: c
28. 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
Ans: a
29. Magnetism of a magnet can be destroyed by
(a) heating
(b) hammering
(c) by inductive action of another magnet
(d) by all above methods
Ans: d
30. Core of an electromagnet should have
(a) low coercivity
(b) high susceptibility
(c) both of the above
(d) none of the above
Ans: c
