Q.1.
Magnetic field produced by electrons in atoms and molecules is due to their
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0%
a) spin motion only
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100%
b) orbital motion only
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0%
c)spin and orbital motion
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0%
d)neither spin nor orbital motion
Q.2.
A bar magnet of magnetic moment M is placed in a uniform magnetic field of induction B such that it makes an angle θ with B. Then the position of stable equilibrium of magnet is given by θ equal to
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100%
a) zero
-
0%
b) 45°
-
0%
c)90°
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0%
d)180°
Q.3.
The magnetic moment of atomic hydrogen is equal to
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0%
a) zero
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0%
b) ½ µB
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50%
c) µB
-
50%
d) (3/2)µB
Q.4.
A permanent magnet
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a)attracts all substances
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0%
b) attracts only ferromagnetic substances
-
50%
c)attracts ferromagnetic substances and repels all others
-
50%
d)attracts some substances and repels other
Q.5.
An isolated magnetic dipole is
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a) a fictitious quantity
-
50%
b) is made of soft iron only
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50%
c)is made of any ferromagnetic material
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0%
d)is made of any diamagnetic material
Q.6.
The angle of dip is the angle
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50%
a) between the vertical component of earth's magnetic field and magnetic meridian
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50%
b) between vertical component of earth's magnetic field and geographic meridian
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c)between earth's magnetic field direction and horizontal direction
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d)between the magnetic meridian and geographic meridian
Q.7.
The line joining the points of zero horizontal components of earth's field is called [ MNR 1987]
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a) magnetic meridian
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b) magnetic axis
-
50%
c) magnetic line
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50%
d) magnetic equator
Q.8.
A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. the work done in rotating the magnet slowly from direction parallel to a horizontal magnetic field of 4 ×10-4 T to a direction 60° from the field will be [ MPPMT 1995]
-
50%
a)0.2J
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0%
b) 2.0 J
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0%
c)4.18 J
-
50%
d)2 × 102 J
Q.9.
The magnetic moment of a single atom of a diamagnetic substance is
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50%
a) zero
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0%
b) less than zero
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50%
c)slightly more than zero
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0%
d)much more than zero
Q.10.
The value of horizontal component of earth's magnetic field at a place is 0.36 × 10-4 weber per metreIf at that place, the angle of dip is 60°, the value of vertical component of earth's magnetic field in weber per metre2 is about
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a) 0.12 ×10-4 Wb/m2
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100%
b) 0.24 ×10-4 Wb/m2
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0%
c)0.4 ×10-4 Wb/m2
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0%
d)0.62 ×10-4 Wb/m2
Q.11.
Above Curie temperature a paramagnetic substance becomes
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a) paramagnetic
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0%
b) diamagnetic
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100%
c) ferromagnetic
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d) super conductor
Q.12.
Three identical bar magnets each of magnetic moment M, are placed in the form of an equilateral triangle with north pole of one touching the south pole of other as shown in figure. The net magnetic moment of he system is
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a)zero
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100%
b) 3M
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0%
ac)3M/2
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0%
d)M√3
Explanation
Q.13.
A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. the time period of vibration is found to be 2 seconds. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 second. Then the angle of dip is
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a) 0°
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100%
b) 30°
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0%
c)45°
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0%
d)90°
Q.14.
The magnetic induction in air at a distance d from the centre of bar magnet of length 2l along the axis is ( of pole strength m unit):
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a) m/d
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0%
b) 2md/(d2 - l2)2
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0%
c)m(d2 - l2)
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100%
d)m/(d2 - l2)
Q.15.
Substances which are magnetized in a magnetic field in opposite direction are called [ CPMT 1993]
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a) Diamagnetic
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0%
b) Paramagnetic
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100%
c) Ferromagnetic
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0%
d) NOn-magnetic
Q.16.
The time of vibration of dip needle vibrating in the vertical plane in the magnetic meridian in 3 seconds. When the same magnetic needle is made to vibrate in the horizontal plane , the time of vibration is 3√2 seconds. then the angle of dip is
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a)30°
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0%
b) 45°
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100%
c)60°
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0%
d)90°
Explanation
Q.17.
Magnetic lines of forces .. [ MPPMT 1994]
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0%
a) always intersect
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0%
b) are always closed
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0%
c)tend to crowed far away from the poles of magnet
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100%
d)do not pass through vacuum
Q.18.
The plane of the dip circle is set in the geographical meridian and the apparent dip is θIt is then set in a vertical plane perpendicular to the geographical meridian, the apparent dip becomes θthe angle of declination 'a' at that place is given by
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a) tanα=√[tanθ1tanθ2]
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b) tanα=√[(tanθ1)2 + (tanθ2)2]
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100%
c)tanα=tanθ1 /tanθ2
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0%
d)tanα=tanθ2 /tanθ1
Explanation
Q.19.
When a magnetic field is applied in a direction perpendicular to the direction of cathode rays, then their
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0%
a) energy decreases
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0%
b) energy increases
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100%
c) momentum increases
-
0%
d) momentum and energy remains unchanged
Q.20.
The coil of a tangent galvanometer is put in magnetic meridian
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a)to avoid the magnetic effect of the erath field
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b) to produce intense magnetic field at the centre of coil
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c)to produce a field at right angle to earth's field
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100%
d)to avoid error due to parallax
Q.21.
A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.16 Tesla experiences a torque of magnitude 0.032 Joule. the magnetic moment of the bar magnet will be
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100%
a) 0.23 joule/tesla
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0%
b) 0.40 joule/tesla
-
0%
c)0.80 joule/tesla
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0%
d)zero
Q.22.
A bar magnet 8cm long is placed in the magnetic meridian with the N-pole pointing towards geographical north. Two neutral points separated by a distance of 6cms are obtained on the equatorial axis of the magnet If H=3.2 ×10-5 tesla then the pole strength of the magnet is
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0%
a) 5 ab-amp × cm
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0%
b) 10 ab-amp × cm
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0%
c)2.5 ab-amp × cm
-
100%
d)20 ab-amp × cm
Explanation
Q.23.
Magnetic line of force due to bar magnet do not intersect because
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0%
a) a point always has a single net magnetic field.
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0%
b) the lines have similar charges and so repel each other
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0%
c) the lines always diverge from a single point
-
100%
d) the lines need magnetic lenses to be made to intersect
Q.24.
A magnet is suspended horizontally in the earth's magnetic flux. When it is displaced and then released, it oscillates in a horizontal plane with a period T. If a piece of wood of the same moment of inertia ( about the axis of rotation) as the magnet is attached to the magnet what would be the new period of oscillation of the system become?
-
100%
a)T/3
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0%
b) T/2
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0%
c)T/√2
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0%
d)T√2
Q.25.
The earth's magnetic field at a certain place has horizontal component 0.3 gauss and the total strength 0.5 gauss. The angle of dip is [ MPPMT 1995]
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0%
a) tan-1(3/4)
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0%
b) sin-1(3/4)
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0%
c)tan-1(4/3)
-
100%
d)sin-1(3/5)
Q.26.
Ferromagnetics own their properties due to
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0%
a) filled inner subshells
-
0%
b) vacant inner subshells
-
100%
c)partially filled inner subshells
-
0%
d)all the sub-shell equally filled
Q.27.
Points A and B are situated along the extended axis of 2 cm long bar magnet at distance x and 2x cm respectively from the pole nearer to the points. The ratio of the magnetic fields at A and B will be [ CPMT 1986]
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0%
a) 4 : 1 exactly
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0%
b) 4 : 1 approximately
-
100%
c) 8 : 1 exactly
-
0%
d) 8 : 1 approximately
Q.28.
A magnet 10 cm long and having a pole strength 2 amp-m is deflected through 30° from the magnetic meridian is 0.32 ×10-4 Tesla. The value of deflecting couple is
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a)16 × 10-7 N-m
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0%
b) 32 × 10-7 N-m
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0%
c)45 × 10-7 N-m
-
100%
d)64 × 10-7 N-m
Q.29.
The period of oscillations of magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be
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0%
a) 1.0 sec
-
0%
b) 0.5 sec
-
0%
c)0.25 sec
-
100%
d)2.0 sec
Explanation
Q.30.
The period of oscillation of a bar magnet in a vibration magnetometer is 2 sec. the period of oscillation of a bar magnet whose magnetic moment is 4 times that of 1st magnet is
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0%
a) 4 sec
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0%
b) 1 sec
-
100%
c)2 sec
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0%
d)0.5 sec