Q.1.
Two isolated point poles of strengths 30 amp × metres and 60 amp × metres are placed at a distance of 0.3 metre. Then the force of repulsion is
-
0%
a) 2 dynes
-
0%
b) 2 × 10-5 newton
-
0%
c) 2 × 10-3 newton
-
100%
d) 2 × 10-4 newton
Q.2.
Each pole of a bar magnet of moment 780 units experiences a force of 1.56 × 105 when placed in a uniform field of 0.4 S.I. units. the length of the bar is ..[ ISM Dhanbad 1994]
-
100%
a)0.20 m
-
0%
b) 2.0 m
-
0%
c)0.002 m
-
0%
d)200 m
Q.3.
Two short bar magnet with pole strengths of 600 ab-amp × cm and 100 ab-amp × cm are placed with their axes in the same vertical line with similar poles facing each other. Each magnet has a length of 1cm. When the separation between the nearer pole is 1cm the weight of the upper magnet is supported by the repulsive force between the magnets. If g is 1000 gm/sec2, then the mass of the upper magnet is
-
100%
a) 100 gm
-
0%
b) 55 gm
-
0%
c)77.5 gm
-
0%
d)45 gm
Explanation
Q.4.
The magnetic needle of an oscillation magnetometer makes 10 oscillations per minute under the action of earth's magnetic field alone. When a bar magnet is placed at some distance along the axis of the needle, it makes 14 oscillations per minutes. If the bar magnet is turned so that its poles interchanged their positions, then the new frequency of oscillation of the needle is
-
0%
a) 10 vibrations per minute
-
100%
b) 14 vibrations per minute
-
0%
c)4 vibrations per minute
-
0%
d)2 vibrations per minute
Explanation
Q.5.
The magnetic moment of atomic neon equal to Where µo is Bohr Magneton
-
0%
a) 0
-
0%
b) (1/2) µo
-
100%
c) µo
-
0%
d) 93/2)µo
Q.6.
The major contribution of magnetism in substances is due to
-
0%
a)orbital motion of electrons
-
0%
b) spin motion of electrons
-
100%
c)equally due to orbital and spin motions of electrons
-
0%
d)hidden magnets
Q.7.
The time period of a freely suspended magnet does not depend upon
-
100%
a) length of magnet
-
0%
b) the pole strength of the magnet
-
0%
c)the horizontal component of magnetic field of the earth
-
0%
d)the length of the suspension
Q.8.
On the application of appropriate steady magnetic field, a high speed electron travelling horizontally through vacuum may be given a net initial acceleration
-
0%
a) in any direction
-
100%
b) only upward, downward or side ways
-
0%
c)only forward or backwards
-
0%
d)in any direction except forward or backwards
Q.9.
For paramagnetic material, the dependence of the magnetic susceptibility X on the absolute temperature T is given by [raj. PMT 11996]
-
0%
a) X ∝ T
-
100%
b) X ∝ constant ×T
-
0%
c) X ∝ (1/T)
-
0%
d) X=constant
Q.10.
The magnetic induction and the magnetic field inside the iron core of an electromagnet is 1.07 weber per metre2 and 150 ampere per metre. then the relative permeability of this iron is
-
0%
a)1.07/150
-
100%
b) 10-7/4π
-
0%
c)1.07 × 10-7 / 150 × 4π
-
0%
d)1.07 × 10+7 / 150 × 4π
Q.11.
The time period of freely suspended magnet does not depend upon
-
0%
a) length of the magnet
-
0%
b) the pole strength of the magnet
-
0%
c)the horizontal component of magnetic field of earth
-
100%
d)torsional rigidity of the suspension
Q.12.
The relationship between µr and Χ ( chi) is
-
0%
a) µr=1 + Χ
-
100%
b) Χ=µr + 1
-
0%
c)Χ=µrµo
-
0%
d)Χ=µr/µo
Q.13.
Metals getting magnetized by orientation of atomic moments in external magnetic field are called
-
0%
a) diamagnetic's
-
0%
b) paramagnetics
-
100%
c) ferromagnetics
-
0%
d) antimagnetic
Q.14.
When a diamagnetic substance is brought near N or S pole of a bar magnet it is [ EAMCET 1995]
-
0%
a)Attracted
-
0%
b) Repelled
-
0%
c)Attracted by N and repelled by S pole
-
100%
d)Repelled by N pole and attracted by S pole
Q.15.
Two short magnets are placed on a piece of cork which floats on water. The magnets are so placed that the axis of one produced bisects the axis of the other at right angle. then the cork
-
0%
a) rotates only
-
0%
b) moves bodily only
-
100%
c)has neither transnational nor rotational motion
-
0%
d)has transnational as well as rotational motion
Q.16.
The magnetic field due to a magnetic dipole of magnetic moment M at a point at a distance d from its centre on a line inclined at an angle θ with the axis is given by
-
0%
a) M/d3
-
100%
b) M/d2
-
0%
c)2M/d3
-
0%
d)(M/d3) √( 1+3cos2θ)
Q.17.
I is the total intensity of earth's magnetic field, H its horizontal component and V the vertical component, then these are related as
-
0%
a) I=V2 + H2
-
0%
b) I=V + H
-
100%
c) I2=V + H
-
0%
d) I2=V2 + H2
Q.18.
A compass needle is placed at the magnetic pole. the compass needle [ CET 1994]
-
0%
a)points south-east
-
0%
b) points east-west
-
100%
c)may stay in any direction
-
0%
d)becomes vertical
Q.19.
The magnetic susceptibility for diamagnetic material is [ AMU 1995]
-
0%
a) small and negative
-
0%
b) small and positive
-
100%
c)large and positive
-
0%
d)large and negative
Q.20.
A steel wire of length l has a magentic moment M. It is bend into a semicircular arc. the new magnetic moment is .. [ BHU 1995]
-
0%
a)M
-
0%
b)2M/π
-
0%
c)M/l
-
100%
d)M × l
Q.21.
The angle of dip is θ at a place where the horizontal and vertical components of earth's magnetic field are equal. the value of θ is [ SCRA 1994]
-
0%
a) 0°
-
100%
b) 30°
-
0%
c) 45°
-
0%
d) 60°
Q.22.
The value of horizontal component of earth's magnetic field at a place is 0.367 × 10-4 weber per metreIf at this place, the angle of dip is 60°, the value of vertical component of earth's magnetic field in weber per metre2 is about [ MP MPT 1985]
-
0%
a)0.12 × 10-4
-
100%
b) 0.24 × 10-4
-
0%
c)0.40 × 10-4
-
0%
d)0.62 × 10-4
Q.23.
A sample of cast Iron exhibits a magnetic field B=0.5 T, where the magnetic intensity H=10 A/m. At this value of M, the permeability of cast Iron will be
-
0%
a) 0.5 T/mA
-
100%
b) 5 TA/m
-
0%
c)0.5T/mA
-
0%
d)5TA/m
Q.24.
The temperature at and above which a ferromagnetic material becomes paramagnetic is called [ SCRA 1994]
-
0%
a) critical temperature
-
0%
b) inversion temperature
-
100%
c)Curie temperature
-
0%
d)Debye temperature
Q.25.
The hysteresis cycle for the material of transformer core is
-
0%
a) short and wide
-
0%
b) tall and narrow
-
0%
c) tall and wide
-
100%
d) short and narrow
Q.26.
Magnetic field is caused by
-
0%
a)stationary charge
-
0%
b) a moving positive charge only
-
0%
c)a moving negative charge only
-
100%
d)moving positive and negative charges both
Q.27.
Magnetic permeability is maximum for
-
0%
a) diamagnetic
-
0%
b) paramagnetic's
-
0%
c)ferromagnetic
-
100%
d)none of the above
Q.28.
A magnet is placed horizontally on a paper. Then the neutral point obtained on the paper is
-
0%
a) 1 only
-
0%
b) 2
-
0%
c)3
-
100%
d)0
Q.29.
Susceptibility is positive and large for [ BHU 1995]
-
0%
a) paramagnetic substance
-
0%
b) ferromagnetic substance
-
0%
c) diamagnetic substance
-
100%
d) non-magnetic substance
Q.30.
The magnetic field due to a short magnet at a point in tanA position ( end position) is 200 gauss. Then the magnetic field at the same distance in tanB position ( broad side - on position) is
-
0%
a)200 gauss
-
0%
b) 400 gauss
-
100%
c)50 gauss
-
0%
d)100 gauss