JEE Questions for Physics Magnetism And Matter Quiz 2 - MCQExams.com

The coercivity of a small magent where the ferromagnet gets demagnetised is 3 × 103A/m. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetised when inside the solenoid is
  • 30 mA
  • 60 mA
  • 3 A
  • 6 A
The intensity of magnetisation of a bar magnet is 5.0 ×104 Am-1 . The magnetic length and the area of cross-section of the magnet are 12 cm and 1 cm2 respectively. The magnitude of magnetic moment of this bar magnet is ( in SI unit )
  • 0.6
  • 1.3
  • 1.24
  • 2.4
Ferromagnetic materials used in a transformer must have
  • low permeability and high hysterisis loss
  • high permeability and low hysterisis loss
  • high permeability and high hysterisis loss
  • low permeability and low hysterisis loss
Resultant force acting on a diamagnetic material in a magnetic field is in direction
  • from stronger to the weaker part of the magnetic field
  • from weaker to the stronger part of the magnetic field
  • perpendicular to the magnetic field
  • in the direction making 60° to the magnetic field
Relative permittivity and permeability of a material are εr and μr , respectively. Which of the following values of these quantities are allowed for a diamagnetic material?
  • εr = 0.5 , μr = 1.5
  • εr = 1.5 , μr = 0.5
  • εr = 0.5 , μr = 0.5
  • εr = 1.5 , μr = 1.5
Electromagnets are made of soft iron because soft iron has
  • low susceptibility and low retentivity
  • low susceptibility and high retentivity
  • high permeability and low retentivity
  • high permeability and high coercivity
  • low permeability and low retentivity
Which one of the following characteristics is not associated with a ferromagnetic material?
  • It is strongly attracted by a magnet
  • It tends to move from a region of strong magnetic field to a region of low magnetic field
  • Its origin is the spin of electrons
  • Above the Curie temperature, it exhibits paramagnetic properties
  • Its magnetic susceptibility is large and positive
A paramagnetic substance of susceptibility 3 × 10-4 is placed in a magnetic field of 4 × 10-4 Am-1 . Then, the intensity of magnetisation in the unit of Am -1 is
  • 1.33 × 108
  • 0.75 × 10-8
  • 12 × 10-8
  • 14 × 10-8
  • 1.2 × 10-8
A paramagnetic liquid is taken in a U-tube and arranged so that, one of its limbs is kept between pole pieces of the magnet. The liquid level in the limb
  • goes down
  • rises up
  • remains same
  • first goes down and then rises
Magnetic susceptibility of a diamagnetic substance
  • decreases with temperature
  • is not affected by temperature
  • increases with temperature
  • first increases then decreases with temperature
The materials suitable for making electromagnets should have
  • high retentivity and high coercivity
  • low retentivity and low coercivity
  • high retentivity and low coercivity
  • low retentivity and high coercivity
At a temperature of 30°C, the susceptibility of a ferromagnetic material is found to be χ . Its susceptibility at 333°C is
  • χ
  • 0.5χ
  • 2χ
  • 11.1χ
  • 0.09χ
A frog can be levitated in magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
  • paramagnetic
  • diamagnetic
  • ferromagnetic
  • anti-ferromagnetic
The magnetic susceptibility of a material of a rod is 499. The absolute permeability of vacuum is 4π × 10-7 Hm-1. The absolute permeability of the material of rod is
  • π × 10-4 Hm-1
  • 2π × 10-4 Hm-1
  • 3π × 10-4 Hm-1
  • 4π × 10-4 Hm-1
Curie temperature is the one above which
  • paramagnetic substance changes to ferromagnetic
  • paramagnetic changes to diamagnetic
  • diamagnetic changes to paramagnetic
  • ferromagnetic changes to paramagnetic
When a ferromagnetic material is heated to temperature above its curie point., the material
  • is permanently magnetised
  • remains ferromagnetic
  • behaves like a diamagnetic material
  • behaves like a paramagnetic material
For a paramagnetic material, the dependence of the magnetic susceptibility χ on the absolute temperature is given as
  • χ ∝ T
  • χ ∝ 1/T2
  • χ ∝ 1/T
  • independent
If a magnet is suspended at an angle 30° to the magnet meridian, the dip of needle makes an angle of 45° with the horizontal, the real dip is

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  • 2)
    Physics-Magnetism and Matter-77841.png

  • Physics-Magnetism and Matter-77842.png

  • Physics-Magnetism and Matter-77843.png
At a certain place the angle of dip is 60° and the horizontal component of the earth's magnetic field (BH ) is 0.8 × 10-4 T. The earth's overall magnetic field is
  • 1.5 × 10-4 T
  • 1.6 × 10-3 T
  • 1.5 × 10-3 T
  • 1.6 × 10-4 T
The angle of dip at a certain place on the earth is 60° and the magnitude of the earth's horizontal component of magnetic field is 0.26 G. The magnetic field at the place on the earth is
  • 0.13 G
  • 0.26 G
  • 0.52 G
  • 0.65 G
A magnet performs 10 oscillations per minute in a horizontal plane at a place where, the angle of dip is 45° and the total intensity is 0.707 unit. The number of oscillations per minute at a place where dip angle is 60° and total intensity is 0.5 CGS unit, will be
  • 5
  • 7
  • 9
  • 11
A short bar magnet of magnetic moment 255 JT-1 is placed with its axis perpendicular to the earth's field direction. At what distance from the centre of the magnet, the resultant field is inclined at 45° with the earth's field, H= 0.4 ×10-4 T ?
  • 5 m
  • 1.08 m
  • 2.5 m
  • 0.25 m
The angle of dip at a place is 37° and the vertical component of the earth's magnetic field is 6 × 10-5 T. The earth's magnetic field at this place is (tan 37° = 3/4)
  • 7 × 10-5 T
  • 6 × 10-5 T
  • 5 × 10-5 T
  • 10-4 T
  • 4 × 10-5 T
Two short magnets have equal pole strengths but one is twice as long as the other. The shorter magnet is placed 20 cm in tan A position from the compass needle. The longer magnet must be placed on the other side of the magnetometer for no deflection at a distance equal to
  • 20 cm
  • 20 × (2)1/3 cm
  • 20 × (2)2/3 cm
  • 20 × (cm
The magnetic needle of a tangent galvanometer is deflected at an angle of 30° due to a current in its coil. The horizontal component of the earth's magnetic field is 0.34 × 10-4 T, then magnetic field at the centre of the coil due to current.
  • 1.96 × 10-5 T
  • 1.96 × 10-4 T
  • 1.96 × 104 T
  • 1.96 × 105 T
A bar-magnet of moment of inertia 49 × 10-2 kg m2 vibrates in a magnetic field of induction 0.5 × 10-4 T. The time period of vibration is 8.8 s The magnetic moment of the bar magnet is
  • 350 Am2
  • 490 Am2
  • 3300 Am2
  • 5000 Am2
A long magnet is cut into two equal parts, such that the length of each half is same as that of original magnet. If the period of original magnet is T, the period of new magnet is
  • T
  • T/2
  • T/4
  • 2T
The magnet of a vibration magnetometer is heated so as to reduce its magnetic moment by 19%. By doing this the periodic time of the magnetometer will
  • increase by 19%
  • decrease by 19%
  • increase by 11%
  • decrease by 21%
A tangent galvanometer has a reduction factor of 1 A and it is placed with the plane of its coil perpendicular to the magnetic meridian. The deflection produced when a current of 1 A is passed through it is
  • 60°
  • 45°
  • 30°
  • None of these
With a standard rectangular bar magnet of length (l ), breadth (b << l ) and magnetic moment M, the time period of the magnet in a vibration magnetometer is 4s. If the magnet is cut normal to its length into four equal pieces, the time period (in second) with one of the pieces is
  • 16
  • 2
  • 1
  • 1/4
0:0:1


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