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
  • a) 4.38 sec
  • b) 0.38 sec
  • c) 2.38 sec
  • 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
  • a)25/36
  • b) 36/25
  • c)5/6
  • 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
  • a) 4
  • b) 17/8
  • c)8/17
  • 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 ..
  • a) 3 × 108 A/am
  • b) 12 × 108 A/m
  • c)12 A/m
  • 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
  • a) 102
  • b) 100
  • c) 104
  • d) 101
Q.6
The correct curve between χ and 1/T for paramagnetic is
  • a)
    ch-17_qn-213choice_img_no1.png
  • b)
    ch-17_qn-213choice_img_no2.png
  • c)
    ch-17_qn-213choice_img_no3.png
  • d)
    ch-17_qn-213choice_img_no4.png
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
  • a) 106 A/m
  • b) 104 A/m
  • c)102 A/m
  • 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
  • a) pole strength
  • b) magnetic moment
  • c)intensity of magnetization
  • 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
  • a) 2 × 10-3 N
  • b) 2 × 10-4 N
  • c) 2 × 105 N
  • d) 2 × 10-5 N
Q.10
Magnetic lines of force are
  • a)continuous
  • b) discontinuous
  • c)some times continuous and some times discontinuous
  • d)nothing can be said
Q.11
Unit of magnetic moment are
  • a) JT
  • b) JT-1
  • c)Am2
  • d)Am-2
Q.12
Units of pole strength of magnet are
  • a) A m-1
  • b) A m2
  • c) A m-2
  • d)A m
Q.13
A tiny loop of current behaves as magnetic dipole
  • a) true
  • b) falls
  • c) may be true or falls
  • d) nothing can be said
Q.14
Magnetic field intensity due to a dipole various as dn where n=...
  • a)2
  • b) -2
  • c)3
  • d)-3
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 ...
  • a) 0.36 J/T
  • b) 0.72 J/T
  • c)0.18 J/T
  • 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
  • a) 7.9 × 10-24 Am2
  • b) 9.7 × 10-24 Am2
  • c)9.7 × 1024 Am2
  • d)7.9 × 1024 Am2
Q.17
The dimensions of magnetic permeability are
  • a) [MLT-2A-2]
  • b) [ML2T-2A-2]
  • c) [ML2T-2A-1]
  • 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
  • a)0.15 amp ×m2
  • b) 0.3 amp × m2
  • c)0.45 amp × m2
  • 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
  • a) 1 × 100-5 Nm
  • b) 1.5 × 100-5 Nm
  • c)2 × 100-5 Nm
  • d)2.5 × 100-5 Nm
Q.20
In the un magnetized state, magnetic domains of a magnetic substance are oriented at
  • a) 60°
  • b) 90°
  • c)Randomly
  • d)zero
Q.21
The time period of freely suspended magnet does not depend upon
  • a) length of magnet
  • b) pole strength of magnet
  • c) horizontal component of earth's field
  • d) length of the suspension
Q.22
The magnetic induction B and the force F on a pole m are related by
  • a)B=mF
  • b) F=B/m
  • c)F=Bm
  • 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
  • a) 1 N
  • b) 1.28 N
  • c)2 N
  • 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
  • a) 20 Wb/m2
  • b) 50 Wb/m2
  • c)112.5 T
  • d)2.0 T
Q.25
Magnetic potential at a point distance d from a magnetic pole of strength m is
  • a)
    ch-17_qn-232choice_img_no1.png
  • b)
    ch-17_qn-232choice_img_no2.png
  • c)
    ch-17_qn-232choice_img_no3.png
  • d) None of these
Q.26
S.I. unit of magnetic permeability is
  • a)A-m
  • b) Am2
  • c)H-m
  • d)H/m
Q.27
Force between two magnetic poles depends on
  • a) pole strength only
  • b) distance only
  • c)medium only
  • 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]
  • a) - B . M
  • b)M × B
  • c)- M × B
  • 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
  • a)1 sec
  • b) 4 sec
  • c)8 sec
  • d)0.5 scc
Q.30
A point at which two or more magnetic fields cancel each other is called
  • a) focal point
  • b) inverse point
  • c)neutral point
  • d)none of the above
0 h : 0 m : 1 s