Q.1
The force experienced by a pole of strength 100 A-m at a distance of 0.2m from a short magnet of length 5cm and pole strength of 200A-m on its axial line will be
  • a) 2.5 × 10⁻² N
  • b) 2.5 × 10⁻³ N
  • c)5.0 × 10⁻² N
  • d)5.0 × 10⁻³ N
Q.2
A magnet 10 cm long has a pole strength of 12 A-m. Find the magnitude of magnetic field strength B at a point on its axis at a distance of 20 cm from it. What would be the value of B, if the point were to lie at the same distance on equatorial of magnet
  • a) 3.4 × 10⁻⁵ T
  • b) 1.4 × 10⁻⁵ T
  • c) 1.7 × 10⁻⁵ T
  • d) 0.85 × 10⁻⁵ T
Q.3
A magnet of moment M is lying in a magnetic field of induction B. W1 is the work done in turning it from 0° to 60 ° and W2 is the work done in turning it from 30° to 90 ° . Then
  • c) W2=2W1
  • a)W₂=W₁
  • b) W₂=W₁/2
  • d) W₂=√3 W₁
Q.4
A bar magnet of magnetic moment 4.0 A-m2 is free to rotate about a vertices axis through its centre. The magnet is released from rest from east-west position. Kinetic energy of the magnet in north-south position will be [ H=25µT)
  • a) 10-2 J
  • b) 10-4 J
  • c)10-6 J
  • d)0
Q.5
The length of bar magnet is 10cm and its pole strength is 10-3 Weber. It is placed in a magnetic field 4 π×10-3 T . in the direction making an angle 30° with electric field direction. The value of torque acting on the magnet will be
  • a) 2π × 10-7 N-m
  • b) 2π × 10-5 N-m
  • c)0.5 × 102 N-m
  • d)none of these
Q.6
A bar magnet with its poles 25 cm apart and pole strength 24.0 A-m rests with its centre on a frictionless pivot. A force F is applied on the magnet at a distance of 12cm from pivot so that it is held in equilibrium at an angle of 30° with respect to a magnetic field of induction 0.25T. The value of force F is
  • a) 5.62 N
  • b) 2.56 N
  • c)6.52 N
  • d)6.25 N
Q.7
A current of 1 mp. is flowing in a coil of 10 turns and with radius 10 cm. Its magnetic moment will be
  • a) 0.314 A-m2
  • b) 3140 A-m2
  • c)100 A-m2
  • d)µ0 A-m2
Q.8
If the radius of circular coil is doubled and the current flowing through in it is halved then new magnetic moment will be if its initial magnetic moment is 4 units
  • a) 8 units
  • b) 4 units
  • c) 2 units
  • d) zero
Q.9
A short bar magnet is placed with its north pole pointing south. the neutral point is 10 cm away from the centre of magnet. If H=0.4 gauss, calculate magnetic moment of the magnet
  • a)2 Am2
  • b) 1 Am2
  • c)0.1 Am2
  • d)0.2 Am2
Q.10
At any place on earth, the horizontal component of earth's magnetic field is √3 times the vertical component. The angle of dip at that place will be
  • a) 60 °
  • b) 45°
  • c)90°
  • d)30°
Q.11
The tangent law applied when
  • a) magnet is suspended in a uniform magnetic field
  • b) horizontal component of earth's field is present
  • c) there are two magnetic filed's
  • d) there are two uniform magnetic field acting perpendicular to each other
Q.12
The period of oscillation of a freely suspended bar magnet is 4 second. If it is cut into equal parts length wise then the time period of each part will be
  • a)4 sec
  • b) 2 sec
  • c)0.5 sec
  • d)0.25 sec
Q.13
A thin magnetic needle oscillates in a horizontal plane with a period T. It is broken into n equal parts. the time period of each part will be
  • a) T
  • c)Tn2
  • d)T/n
  • b) T/n²
Q.14
The time period of a small magnet in a horizontal plane is T. Another magnet B oscillates at the same place in a similar manner. The size of two magnet is same but the magnetic moment of B is four times that of A. The time period of B will be
  • a) T/4
  • b) T/2
  • c)2T
  • d)4T
Q.15
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.16
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.17
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.18
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.19
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.20
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.21
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.22
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.23
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
  • c) 2 × 105 N
  • a) 2 × 10⁻³ N
  • b) 2 × 10⁻⁴ N
  • d) 2 × 10⁻⁵ N
Q.24
Magnetic lines of force are
  • a)continuous
  • b) discontinuous
  • c)some times continuous and some times discontinuous
  • d)nothing can be said
Q.25
Unit of magnetic moment are
  • a) JT
  • b) JT-1
  • c)Am2
  • d)Am-2
Q.26
Units of pole strength of magnet are
  • a) A m-1
  • b) A m2
  • c) A m-2
  • d)A m
Q.27
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.28
Magnetic field intensity due to a dipole various as dn where n=...
  • a)2
  • b) -2
  • c)3
  • d)-3
Q.29
The dimensions of magnetic permeability are
  • a) [MLT-2A-2]
  • b) [ML2T-2A-2]
  • c) [ML2T-2A-1]
  • d) [M-1LT-2A-1]
Q.30
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
0 h : 0 m : 1 s