The magnetism in a magnet is mainly due to
A)
The orbital motion of the electrons
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B)
The spin motion of the electrons
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C)
The nuclear charge
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D)
None of the above
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Two bars of soft iron exactly same are given. One of them is a magnet. Without using anything more, how would you find which is a magnet
A)
By bringing two bars near and noting which one is attracting. The attracting one is a magnet
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B)
By bringing two bars near and noting which one is repelling. One which repels is an ordinary iron.
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C)
By rubbing one bar with the other and noting which becomes magnet. The bar which is magnetised is an ordinary iron
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D)
One bar is placed flat horizontal on the table and the other bar is held vertical with its one end on the middle of first bar. If there is attraction between the two, the vertical bar is magnet otherwise ordinary iron.
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When a bar magnet is broken into two pieces?
A)
We will have a single pole on each piece
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B)
Each piece will have two like poles
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C)
Each piece will have two unlike poles
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D)
Each piece will lose magnetism
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Along the direction of current carrying wire, the value of magnetic field is?
A)
Zero
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B)
Infinity
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C)
Depends on the length of the wire
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D)
Uncertain
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A temporary magnet is made of
A)
Cast iron
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B)
steel
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C)
Soft iron
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D)
stainless steel
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Of dia, para and ferromagnetism, the universal property of all substances is
A)
Diamagnetism
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B)
Paramagnetism
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C)
Ferromagnetism
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D)
All the above
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In a cassette player, materials used for coating magnetic tapes are
A)
Cobalt
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B)
\[CoF{{e}_{2}}{{O}_{4}}\]
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C)
\[NiF{{e}_{2}}{{O}_{4}}\]
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D)
Nickel
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Curie temperature is the temp. above which
A)
A Ferro magnetic material becomes para magnetic
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B)
A para magnetic material becomes dia magnetic
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C)
A Ferro magnetic material becomes dia magnetic
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D)
A para magnetic material becomes Ferro magnetic
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Which one of the following is not a magnetic material?
A)
Iron
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B)
Nickel
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C)
Aluminium
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D)
Cobalt
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If a magnet is dropped into a coil of wire, it will fall with an acceleration
A)
Equal to g
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B)
More than g
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C)
less than g
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D)
Equal to g in the beginning and then more than g
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A magnet can be demagnetised by
A)
Hammering the magnet
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B)
Putting it in the water
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C)
Cooling it
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D)
Putting it in contact with iron
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If the horizontal and vertical components of the earth's magnetic field are equal at a certain place, the angle of a dip at that place will be
A)
\[30{}^\circ \]
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B)
\[60{}^\circ \]
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C)
\[45{}^\circ \]
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D)
\[90{}^\circ \]
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An electromagnet is made of
A)
Copper
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B)
Nickel
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C)
Soft iron
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D)
Steel
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Which of the following instruments is used to measure magnetic field?
A)
A thermometer
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B)
A pyrometer
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C)
A fluxmeter
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D)
A hygrometer
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A moving charge produces
A)
Neither electric field nor magnetic field
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B)
electro-static field only
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C)
Magnetic field only
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D)
Both magnetic and electro-static field
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A magnetic field is produced by
A)
All currents
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B)
all charges
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C)
Both [a] and [b]
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D)
None of the above
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Eddy currents are produced when
A)
A metal is kept in varying magnetic field
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B)
A circular coil is placed in a magnetic field
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C)
A metal is kept in the steady magnetic field
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D)
A current is passed through a circular coil
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The magnetic compass is not useful for navigation near the magnetic poles. Since
A)
R = 0
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B)
V = 0
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C)
H = 0
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D)
\[\theta =0{}^\circ \]
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The direction of magnetic line of force of a bar magnet is
A)
From south to North Pole
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B)
From north to South Pole
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C)
Across the bar magnet
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D)
From south to North Pole inside the magnet and from north South Pole outside the magnet
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A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis. Of the following physical quantities the one white remains unchanged is
A)
Pole strength
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B)
Magnetic moment
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C)
Intensity of magnetisation *-a [c] For each half \[M=m\times 2\,\ell \] becomes half and volume \[V=a\times 21\] also becomes half therefore, I = M/V, remains constant.
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D)
Moment of inertia
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