Q.1
A bar magnet of length 10cm and having the pole strength equal to 10- weber is kept in the magnetic field having magnetic induction (B) equal to 4π × 10-3 tesla. It makes an angle of 30° with the direction of magnetic induction (B). The value of the torque acting on the magnet is
  • a) 2π × 10-7 newton × metre
  • b)2π × 10-5 newton × metre
  • c)0.5 newton × metre
  • d)0.5 × 102 newton × metre
Q.2
The angle of dip at place i 40.6° and the intensity of the vertical component of the earth's magnetic field V=6 × 10-5 tesla. The total intensity of earth's magnetic field at this place is
  • a) 7 × 10-5 tesla
  • b) 6 × 10-5 tesla
  • c) 5 × 10-5 tesla
  • d) 9.2 × 10-5 tesla
Q.3
Due to earth's magnetic field, charged cosmic ray particles [ CBSE 1997]
  • a)requires greater kinetic energy to reach equator than the pole
  • b) require less kinetic energy to reach the equator than the pole
  • c)can never reach the pole
  • d)can never reach the equator
Q.4
The needle of dip circle when placed at a geometric pole stays long
  • a) south north direction only
  • b) east west direction only
  • c)vertical direction
  • d)none of above
Q.5
The magnetic susceptibility for diamagnetic material is
  • a) small and negative
  • b) small and positive
  • c)large and positive
  • d)large and negative
Q.6
The correct value of dip angle at a place is 45°. If the dip circle is rotated 45° out of the meridian, then the tangent of the angle of apparent dip is
  • a) 1
  • b) 1/√2
  • c) √2
  • d) 1/2
Q.7
At certain place, the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.5 oersted. the earth's total magnetic field ( in oersted) is
  • a)√3
  • b) 1
  • c)1 / √3
  • d)1/2
Q.8
Two small magnets each of magnetic moment 10 Am2 are placed in end on position 0.1m apart from their centres. The force acting between them is
  • a) 0.6 × 107 N
  • b) 0.006 × 107 N
  • c)0.6 N
  • d)0.06 N
Q.9
At a certain place, horizontal component is √3 times the vertical component. the angle of dip at this place is
  • a) 0
  • b) π/3
  • c)π/6
  • d)none of the above
Q.10
A steel wire of length l has a magnetic moment M. It is then bent into a semicircular arc. the new magnetic moment is
  • a) M
  • b) 2M/π
  • c) M/l
  • d) M × l
Q.11
Two identical magnetic dipoles of magnetic moment 1.0 Am2 each, placed at sepration of 2m with their axis perpendicular to each other. The resultant magnetic field at a point midway between the dipole is
  • a)5 × 10-7 T
  • b) √5 × 10-7 T
  • c)10-7 T
  • d)2 × 10-7 T
Q.12
The force between two short bar magnets with magnetic moments M1 and M2 whose centres are r metre apart is 8N, when their axes are in same line. If the sepration is increased to 2r, the force between them is reduced to
  • a) 4N
  • b) 2N
  • c)1N
  • d)0.5N
Q.13
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.14
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.15
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
  • a)W2=W1
  • b) W2=W1/2
  • c) W2=2W1
  • d) W2=√3 W1
Q.16
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.17
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.18
A magnet having a magnetic moment of 1.0 × 104 J/T is free to rotate in horizontal plane where a magnetic field 4 × 10-5 T exists. Find the work done in rotating the magnet slowly done in rotating the magnet slowly from a direction parallel to the field to a direction 60° from the field
  • a) 0.4 J
  • b) 2 J
  • c) 0.2 J
  • d) 1 J
Q.19
A magnetic needle of magnetic moment 60 amp-m2 experience a torque of 1.2 ×10-3 N-m directed in geographical north. If the horizontal intensity of earth's magnetic field at that place is 40 Wb/m2, then the angle of direction will be
  • a)30°
  • b) 45°
  • c)60°
  • d)90°
Q.20
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.21
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.22
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.23
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.24
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.25
The horizontal component of earth's magnetic field at any place is 0.36×10-4 Weber/mIf the angle of dip at that place is 60° then the value of vertical component of earth's magnetic field will be ( in Wb/m2)
  • a) 0.12 × 10-4
  • b) 0.24 ×10-4
  • c)0.40 ×10-4
  • d)0.62 ×10-4
Q.26
The radius of the coil of tangent galvanometer is 16 cm. How many turns of the wire should be used if a current of 40 mA is to be produced a deflection of 45°, given horizontal component of earth's field is 0.36 ×10-4 T.
  • a) 458
  • b) 229
  • c) 200
  • d) 115
Q.27
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.28
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.29
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
  • b) T/n2
  • c)Tn2
  • d)T/n
Q.30
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
0 h : 0 m : 1 s