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
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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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Main causes of noisy solenoid are
A. strong tendency of fan out of laminations at the end caused by repulsion 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
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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
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Gilbert is a unit of
A. electromotive force
B. magnetomotive force
C. conductance
D. permittivity
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Which of the following is the unit of magnetic flux density?
A. Weber
B. Lumens
C. Tesla
D. None of the above
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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
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The magnetomotive 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
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The relative permeability is less than unity is case of
A. ferromagnetic materials
B. ferrites
C. non-ferrous materials
D. diamagnetic materials
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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 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
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A material which is slightly repelled by a magnetic field is known as
A. ferromagnetic material
B. diamagnetic material
C. paramagnetic material
D. conducting material
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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) both in the same way
D. none of the above
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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
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Reciprocal of permeability is
A. reluctivity
B. susceptibility
C. permittivity
D. conductance
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Susceptibility is positive for
A. non-magnetic substances
B. diamagnetic substances
C. ferromagnetic substances
D. none of the above
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Which of the following materials are diamagnetic?
A. Silver
B. Copper
C. Silver and copper
D. Iron
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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
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For which of the following materials the saturation value is the highest?
A. Ferromagnetic materials
B. Paramagnetic materials
C. Diamagnetic materials
D. Ferrites
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Magnetic moment is a
A. pole strength
B. universal constant
C. scalar quantity
D. vector quantity
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