Q.1
If θ1 and θ2 be the apparent angles of dip observed in two vertical planes angles to each other then the true angle of dip θ is given by .. [ NEET 2017]
  • a) cot2 θ= cot2 θ1 + cot2 θ2
  • b) tan2 θ= tan2 θ1 + tan2 θ2
  • c) cot2 θ= cot2 θ1 - cot2 θ2
  • d) tan2 θ= tan2 θ1 - tan2 θ2
Q.2
A bar magnet having a magnetic moment of 2×104 JT-1 is free to rotate in a horizontal plane. A horizontal magnetic field B=6×10⁻¹ T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is .. [ CBSE-PMT 200]
  • a) 12J
  • b) 6J
  • c)2J
  • d)0.6J
Q.3
A short magnet of moment 6.75 Am2 produces a neutral point on its axis. If the horizontal component of earth's magnetic field is 5×10⁻⁵ wb/m2, then distance of the neutral point should be [ SCRA 1994]
  • a) 10 cm
  • b) 20 cm
  • c)30 cm
  • d)40 cm
Q.4
A bar magnet has a magnetic moment equal to 5×10⁻⁵ weber×metre. It is suspended in a magnetic field which has a magnetic induction (B) equal to 8π×10-4 tesla. The magnet vibrates with period of vibration equal to 15 seconds. the moment of inertia of the magnet is [ MPPMT 1993]
  • a) 22.5 kg×m²
  • b) 11.25 kg×m²
  • c) 5.62 kg×m²
  • d) 7.16×10⁻⁷ kg×m²
Q.5
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]
  • a)0.12 × 10⁻⁴
  • b) 0.24 × 10⁻⁴
  • c)0.40 × 10⁻⁴
  • d)0.62 × 10⁻⁴
Q.6
A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. the work done in rotating the magnet slowly from direction parallel to a horizontal magnetic field of 4 ×10⁻⁴ T to a direction 60° from the field will be [ MPPMT 1995]
  • a)0.2J
  • b) 2.0 J
  • c)4.18 J
  • d)2 × 102 J
Q.7
The value of horizontal component of earth's magnetic field at a place is 0.36 × 10⁻⁴ weber per metreIf at that place, the angle of dip is 60°, the value of vertical component of earth's magnetic field in weber per metre2 is about
  • a) 0.12 ×10⁻⁴ Wb/m²
  • b) 0.24 ×10⁻⁴ Wb/m²
  • c)0.4 ×10⁻⁴ Wb/m²
  • d)0.62 ×10⁻⁴ Wb/m²
Q.8
A bar magnet 8cm long is placed in the magnetic meridian with the N-pole pointing towards geographical north. Two neutral points separated by a distance of 6cms are obtained on the equatorial axis of the magnet If H=3.2 ×10⁻⁵ tesla then the pole strength of the magnet is
  • a) 5 ab-amp × cm
  • b) 10 ab-amp × cm
  • c)2.5 ab-amp × cm
  • d)20 ab-amp × cm
Q.9
A magnet 10 cm long and having a pole strength 2 amp-m is deflected through 30° from the magnetic meridian is 0.32 ×10⁻⁴ Tesla. The value of deflecting couple is
  • a)16 × 10⁻⁷ N-m
  • b) 32 × 10⁻⁷ N-m
  • c)45 × 10⁻⁷ N-m
  • d)64 × 10⁻⁷ N-m
Q.10
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.11
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.12
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.13
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.14
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.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
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.17
Force acting on a magnetic pole of 7.5 ×10⁻² A-m is 1.5 N. Magnetic field at the point is
  • c)112.5 T
  • d)2.0 T
  • a) 20 Wb/m²
  • b) 50 Wb/m²
Q.18
A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. the work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of 4×10⁻⁵ T to a direction 60° from the field will be [ MPPMT 1995]
  • a) 0.2 J
  • b) 2.0 J
  • c)4.18 J
  • d)2×102 J
Q.19
If a dip needle is suspended at an angle of 30° to the magnetic meridian, it makes an angle of 45° with the horizontal. The real dip is [ CPMT 1998]
  • a) tan⁻¹ (√3/2)
  • b) tan⁻¹ (√3)
  • c)tan⁻¹ √(3/2)
  • d)tan⁻¹ (2 /√3)
Q.20
A uniform magnetic needle is suspended from its centre by a thread. Its upper end is now loaded with a mass of 50 mg when the needle becomes horizontal. If the strength of each pole is 98.1 ab-amp × cm and g is 981 cm/sec2, then the vertical componenet of the earth's magnetic induction is
  • a)0.50 gauss
  • b) 0.25 gauss
  • c)0.05 gauss
  • d)0.005 gauss
Q.21
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.22
There are 2.0 × 1024 molecular dipoles in a paramagnetic salt. Each has dipole moment 1.5 ×10⁻²³ A-mFind the maximum ( saturation) magnetization in the specimen [ GUJCET 2008]
  • a)30 A-m2
  • b) 20 A-m2
  • c)50 A-m2
  • d)200 A-m2
Q.23
A solenoid is 1.5 m long and its inner diameter is 4.0cm. It has 3 layers of windings of 1000 turns each and carries a current of 2.0 A. The magnetic flux for a cross-section of the solenoid is nearly.....
  • a) 4.1 ×10⁻⁵ Wb
  • b) 5.2 ×10⁻⁵ Wb
  • c)6.31 ×10⁻³ Wb
  • d)2.5 ×10⁻⁷ Wb
Q.24
Two short bar magnets of length 1 cm each have magnetic moments 1.20 Am2 and 1.00 Am2 respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid - point O of the line joining their centre is close to (Horizontal component of earth′s magnetic induction is 3.6 × 10⁻⁵ Wb / m2)
  • a) 3.6 × 10⁻⁵ Wb/m²
  • b) 2.56 × 10⁻⁴ Wb/m²
  • c) 3.50 × 10⁻⁴ Wb/m²
  • d) 5.80 × 10⁻⁴ Wb/m²
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