JEE Questions for Physics Magnetism And Matter Quiz 9 - MCQExams.com

The vertical component of the earth\'s magnetic field is zero at a place where the angle of dip is
  • 0°
  • 45°
  • 60°
  • 90°
A compass needle will show which of the following direction at the earth\'s magnetic pole
  • Vertical
  • No particular direction
  • Bent at 45° to the vertical
  • Horizontal
The north pole of the earth\'s magnet is near the geographical
  • South
  • East
  • West
  • North
The magnetic field of earth is due to
  • Motion and distribution of some material in and outside the earth
  • Interaction of cosmic rays with the current of earth
  • A magnetic dipole buried at the centre of the earth
  • Induction effect of the sun
A short magnet of moment 6.75 Am2 produces a neutral point on its axis. If horizontal component of earth\'s magnetic field is 5 × 10–5 Wb/m2, then the distance of the neutral point should be
  • 10 cm
  • 20 cm
  • 30 cm
  • 40 cm
Due to the earth\'s magnetic field, charged cosmic ray particles
  • Required greater kinetic energy to reach the equator than the poles
  • Required less kinetic energy to reach the equator than the poles
  • Can never reach the equator
  • Can never reach the poles
Two bar magnets with magnetic moment 2 M and M are fastened together at right angles to each other at their centres to form a crossed system, which can rotate freely about a vertical axis through the centre. The crossed system sets in earth\'s magnetic field with magnet having magnetic moment 2M making an angle θ with the magnetic meridian such that

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  • 2)
    Physics-Magnetism and Matter-78147.png

  • Physics-Magnetism and Matter-78148.png

  • Physics-Magnetism and Matter-78149.png
The value of angle of dip is zero at the magnetic equator because on it
  • V and H are equal
  • The value of V and H is zero
  • The value of V is zero
  • The value of H is zero
The angle of dip at a certain place on earth is 60° and the magnitude of earth\'s horizontal component of magnetic field is 0.26 G. The magnetic field at the place on earth is
  • 0.13G
  • 0.26 G
  • 0.52G
  • 0.65G
Time period of a freely suspended magnet does not depend upon
  • Length of the magnet
  • Pole strength of the magnet
  • Horizontal component of earth's magnetic field
  • Length of the suspension thread
Magnetic moments of two bar magnets may be compared with the help of
  • Deflection magnetometer
  • Vibration magnetometer
  • Both of the above
  • None of the above
The time period of oscillation of a freely suspended bar magnet with usual notations is given by

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    Physics-Magnetism and Matter-78153.png

  • Physics-Magnetism and Matter-78154.png

  • Physics-Magnetism and Matter-78155.png
In sum and difference method in vibration magnetometer, the time period is more if
  • Similar poles of both magnets are on same sides
  • Opposite poles of both magnets are on same sides
  • Both magnets are perpendicular to each other
  • Nothing can be said
At a certain place a magnet makes 30 oscillations per minute. At another place where the magnetic field is double, its time period will be
  • 4 sec
  • 2 sec
  • 1/2 sec
  • √2 sec
Two magnets of same size and mass make respectively 10 and 15 oscillations per minute ar certain place. The ratio of their magnetic moments is
  • 4 : 9
  • 9 ; 4
  • 2 : 3
  • 3 : 2
Time period for a magnet is T. It if is divided in four equal parts along its axis and perpendicular to its axis as shown then time period for each part will be
Physics-Magnetism and Matter-78159.png
  • 4 T
  • T/4
  • T/2
  • T
Two tangent galvanometers A and B have coils of radii 8 cm and 16 cm respectively and resistance 8 Ω each. They are connected in parallel with a cell of e.m.f. 4 V and negligible integral resistance. The deflections produced in the tangent galvanometers A and B are 30° and 60° respectively. It A has 2 turns, then B must have
  • 18 turns
  • 12 turns
  • 6 turns
  • 2 turns
Two uniform magnetic fields B and H are perpendicular to each other at a place. When a magnetic needle is placed in the field, it rest making angle 60° and 30° with B and H respectively. The value of B : H is
  • 1 : 2
  • 2 : 1
  • √3 : 1
  • 1 : √3
The radius of the coil of a tangent galvanometer which has 10 turns is 0.1 m. The current required to produce a deflection of 60° (BH = 4 × 10–5T) is
  • 3 A
  • 1.1 A
  • 2.1 A
  • 1.5 A
A magnet oscillating in a horizontal plane has a time period of 2 second at a place where the angle of dip is 30° and 3 seconds at another place where the angle of dip is 60°. The ratio of resultant magnetic fields at the two places is

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    Physics-Magnetism and Matter-78165.png

  • Physics-Magnetism and Matter-78166.png

  • Physics-Magnetism and Matter-78167.png
A magnetic needle is made to vibrate in uniform field H, then its time period is T. It is vibrates in the field of intensity 4H, its time period will be
  • 2T
  • T/2
  • 2/T
  • T
Two bar magnets of the same mass, length and breadth but magnetic moments M and 2M respectively, when placed in same position, have time period 3 sec. What will be the time period when they are placed in different position.
  • √3 sec
  • 3√3 sec
  • 3 sec
  • 6 sec
The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be
  • 2 s
  • 2/3 s
  • 2√3 s
  • 2/√3 s
A magnet is suspended in such a way that it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place where dip angle is 30° and 15 oscillations per minute at a place where dip angle is 60°. The ratio of total earth\'s magnetic field at the two places is

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  • 2)
    Physics-Magnetism and Matter-78173.png

  • Physics-Magnetism and Matter-78174.png

  • Physics-Magnetism and Matter-78175.png
A bar magnet is oscillating in the earth\'s magnetic field with time period T. If its mass is increased four items then its time period will be
  • 4 T
  • 2 T
  • T
  • T/2
Two magnets A and B are identical in mass, length and breadth but has different magnetic moments. In a vibration magnetometer, if the time period of B is twice the time period of A. The ratio of the magnetic moments MA/MB of the magnets will be
  • 1/2
  • 2
  • 4
  • 1/4
A magnet of magnetic moment M oscillating freely in earth\'s horizontal magnetic field makes n oscillations per minute. If the magnetic moment is quadrupled and the earth\'s field is doubled, the number of oscillations made per minute would be

  • Physics-Magnetism and Matter-78179.png
  • 2)
    Physics-Magnetism and Matter-78180.png

  • Physics-Magnetism and Matter-78181.png

  • Physics-Magnetism and Matter-78182.png
A magnetic needle suspended horizontally by an unspun silk fibre, oscillates in the horizontal plane because of the restoring force originating mainly from
  • The torsion of the silk fibre
  • The force of gravity
  • The horizontal component of earth's magnetic field
  • All the above factors
At two places A and B using vibration magnetometer, a magnet vibrates in a horizontal plane and its respecitve periodic time are 2 sec and 3 sec and at these places the earth\'s horizontal components are HA and HB respectively. Then the ratio between HA and HB will be
  • 9 : 4
  • 3 : 2
  • 4 : 9
  • 2 : 3
The time period of a bar magnet suspended horizontally in the earth\'s magnetic field and allowed to oscillate
  • Is directly proportional to the square root of its mass
  • Is directly proportional to its pole strength
  • Is inversely proportional to its magnetic moment
  • Decreases if the length increases but pole strength remains same
0:0:1


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