Q.1.
A magnet makes 10 oscillations per minute at a place where the horizontal component of earth's magnetic field (H) is 0.33 oersted. The time period of the magnet at a place where the value of H is 0.62 oersted will be
-
100%
a) 4.38 sec
-
0%
b) 0.38 sec
-
0%
c) 2.38 sec
-
0%
d) 8.38 sec
Q.2.
A magnet makes 10 oscillations per minute at one place and takes 5 seconds to complete one oscillations at another place. Compare the values of horizontal components of earth's field at two places
-
0%
a)25/36
-
100%
b) 36/25
-
0%
c)5/6
-
0%
d)6/5
Q.3.
The time period of vibration of two magnets is some position is 3 sec. When polarity of weaker magnet is reversed, the combination makes 12 oscillations per minute. compare the magnetic moments of to magnets
-
100%
a) 4
-
0%
b) 17/8
-
0%
c)8/17
-
0%
d)1/4
Q.4.
The magnetic susceptibility of paramagnetic substance is 3 ×10-It is placed in a magnetizing field of 4 × 103 amp/m. The intensity of magnetization will be ..
-
0%
a) 3 × 108 A/am
-
0%
b) 12 × 108 A/m
-
100%
c)12 A/m
-
0%
d)24 A/m
Q.5.
A magnetizing field of 2 × 103 amp/m produces a magnetic flux density of 8π Tesla in an iron rod. the relative permeability of the rod will be
-
0%
a) 102
-
100%
b) 100
-
0%
c) 104
-
0%
d) 101
Q.6.
The correct curve between χ and 1/T for paramagnetic is
-
100%
a)
-
0%
b)
-
0%
c)
-
0%
d)
Q.7.
The mass of an iron rod is 80 gm and its magnetic moment is 10 A-mIf the density of iron is 8 gm/cc then the value of intensity of magnetization will be
-
0%
a) 106 A/m
-
0%
b) 104 A/m
-
100%
c)102 A/m
-
0%
d)10 A/m
Q.8.
A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis, of the following physical quantities the one which remains unchanged is
-
0%
a) pole strength
-
100%
b) magnetic moment
-
0%
c)intensity of magnetization
-
0%
d)moment of inertia
Q.9.
Two isolated point pole of strength 30 A m and 60 A m are placed at a distance of 0.3 m. The force of repulsion
-
0%
a) 2 × 10-3 N
-
0%
b) 2 × 10-4 N
-
100%
c) 2 × 105 N
-
0%
d) 2 × 10-5 N
Explanation
Q.10.
Magnetic lines of force are
-
0%
a)continuous
-
0%
b) discontinuous
-
0%
c)some times continuous and some times discontinuous
-
100%
d)nothing can be said
Q.11.
Unit of magnetic moment are
-
0%
a) JT
-
0%
b) JT-1
-
0%
c)Am2
-
100%
d)Am-2
Q.12.
Units of pole strength of magnet are
-
0%
a) A m-1
-
0%
b) A m2
-
100%
c) A m-2
-
0%
d)A m
Q.13.
A tiny loop of current behaves as magnetic dipole
-
0%
a) true
-
0%
b) falls
-
100%
c) may be true or falls
-
0%
d) nothing can be said
Q.14.
Magnetic field intensity due to a dipole various as dn where n=...
-
0%
a)2
-
100%
b) -2
-
0%
c)3
-
0%
d)-3
Explanation
Q.15.
A short bar magnet place with axis at 30°, with uniform external magnetic field of 0.25 T experiences a torque of 4.5 × 10-2 N-m. Magnetic moment of the magnet is ...
-
0%
a) 0.36 J/T
-
0%
b) 0.72 J/T
-
100%
c)0.18 J/T
-
0%
d)zero
Q.16.
In hydrogen atom, an electron revolves with frequency of 6.8 × 109 megahertz in an orbit of diameter 1.06 Å. The equivalent magnetic moment is
-
100%
a) 7.9 × 10-24 Am2
-
0%
b) 9.7 × 10-24 Am2
-
0%
c)9.7 × 1024 Am2
-
0%
d)7.9 × 1024 Am2
Q.17.
The dimensions of magnetic permeability are
-
0%
a) [MLT-2A-2]
-
0%
b) [ML2T-2A-2]
-
0%
c) [ML2T-2A-1]
-
100%
d) [M-1LT-2A-1]
Q.18.
A circular coil of radius 4cm having 20 turns carries a current of 3A. It is placed in a magnetic field of intensity 0.5 weber/mThe magnetic dipole moment of the coil is
-
0%
a)0.15 amp ×m2
-
0%
b) 0.3 amp × m2
-
0%
c)0.45 amp × m2
-
100%
d)0.6 amp × m2
Q.19.
The magnetic moment of a magnet is 0.1 amp × mIt is suspended in a magnetic field of intensity 3×10-4 weber/mThe couple acting upon it when deflected by 30° from the magnetic field is
-
0%
a) 1 × 100-5 Nm
-
100%
b) 1.5 × 100-5 Nm
-
0%
c)2 × 100-5 Nm
-
0%
d)2.5 × 100-5 Nm
Q.20.
In the un magnetized state, magnetic domains of a magnetic substance are oriented at
-
0%
a) 60°
-
0%
b) 90°
-
0%
c)Randomly
-
100%
d)zero
Q.21.
The time period of freely suspended magnet does not depend upon
-
0%
a) length of magnet
-
0%
b) pole strength of magnet
-
0%
c) horizontal component of earth's field
-
100%
d) length of the suspension
Q.22.
The magnetic induction B and the force F on a pole m are related by
-
0%
a)B=mF
-
0%
b) F=B/m
-
0%
c)F=Bm
-
100%
d)none of these
Q.23.
Calculate force exerted on a point N pole of 3200 A-m placed 10cm away from a point south pole of 30 A-m in air
-
0%
a) 1 N
-
0%
b) 1.28 N
-
0%
c)2 N
-
100%
d)3 N
Q.24.
Force acting on a magnetic pole of 7.5 ×10-2 A-m is 1.5 N. Magnetic field at the point is
-
0%
a) 20 Wb/m2
-
0%
b) 50 Wb/m2
-
100%
c)112.5 T
-
0%
d)2.0 T
Q.25.
Magnetic potential at a point distance d from a magnetic pole of strength m is
-
0%
a)
-
0%
b)
-
100%
c)
-
0%
d) None of these
Q.26.
S.I. unit of magnetic permeability is
-
0%
a)A-m
-
0%
b) Am2
-
0%
c)H-m
-
100%
d)H/m
Q.27.
Force between two magnetic poles depends on
-
0%
a) pole strength only
-
0%
b) distance only
-
100%
c)medium only
-
0%
d)all the three above
Q.28.
A bar magnet of magnetic moment M is placed in magnetic field of induction B. The torque exerted on it is [ GUJCET 2007]
-
0%
a) - B . M
-
0%
b)M × B
-
100%
c)- M × B
-
0%
d)M . B
Q.29.
The period of oscillation of a magnet is a vibration magnetometer is 2 seconds. the period of oscillation of magnet of moment of inertia four times that of first magnet is
-
0%
a)1 sec
-
0%
b) 4 sec
-
0%
c)8 sec
-
100%
d)0.5 scc
Q.30.
A point at which two or more magnetic fields cancel each other is called
-
0%
a) focal point
-
0%
b) inverse point
-
0%
c)neutral point
-
100%
d)none of the above