JEE Questions for Physics Magnetism And Matter Quiz 10

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A small bar magnet A oscillates in a horizontal plane with a period T at a place where the angle of dip is 60°. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, its period will be

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T
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2T

Vibration magnetometer works on the principle of

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Torque acting on the bar magnet
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Force acting on the bar magnet
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Both the force and the torque acting on the bar magnet
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None of the above

Tangent galvanometer is used to measure

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Steady currents
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Current impulses
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Magnetic moments of bar magnets
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Earth's magnetic field

A tangent galvanometer has a coil with 50 turns and radius equal to 4 cm. A current of 0.1 A is passing through it. The plane of the coil is set parallel to the earth\'s magnetic meridian. If the value of the earth\'s horizontal component of the magnetic field is 7 × 10^–5 tesla and µ₀ = 4π × 10^–7 weber/amp × m, then the deflection in the galvanometer needle will be

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45°
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48.2°
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50.7°
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52.7°

A thin rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is T’, then ratio T’ /T is

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2)
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2

A magnetic needle suspended by a silk thread is vibrating in the earth\'s magnetic field. If the temperature of the needle is increased by 500°C, then

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The time period decreases
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The time period remains unchanged
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The time period increases
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The needle stops vibrating

Using a bar magnet P, a vibration magnetometer has time period 2 seconds. When a bar Q (identical to P in mass and size) is placed on top of P, the time period is unchanged. Which of the following statements is true

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Q is of non-magnetic material
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Q is a bar magnet identical to P, and its north pole is placed on top of P' s north pole
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Q is of unmagnetized ferromagnetic material
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Nothing can be said about Q' s properties

The strength of the magnetic field in which the magnet of a vibration magnetometer is oscillating is increased 4 times its original value. The frequency of oscillation would then become

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Twice its original value
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Four times its original value
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Half its original value
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One-fourth its original value

A short magnetic needle is pivoted in a uniform magnetic field of strength 1 T. When another magnetic field of strength √3 T is applied to the needle in a perpendicular direction, the needle deflects through an angle θ, where θ is

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30°
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45°
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90°
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60°

When √3 ampere current is passed in a tangent galvanometer, there is a deflection of 30° in it. The deflection obtained when 3 amperes current is passed, is

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30°
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45°
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60°
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75°

The period of oscillations of a magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be

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1.0 sec
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0.5 sec
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0.25 sec
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2.0 sec

The time period of a freely suspended magnet is 2 sec. If it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be

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4 sec
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2 sec
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-a sec
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1 sec

The bob of a simple pendulum is replaced by a magnet. The oscillations are set along the length of the magnet. A copper coil is added so that one pole of the magnet passes in and out of the coil. The coil is short-circuited. Then which one of the following happens

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Period decreases
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Period does not change
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Oscillations are damped
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Amplitude increases

The period of oscillation of a vibration magnetometer depends on which of the following factors where I is the moment of inertia of the magnet about the axis of suspension, M is the magnetic moment of the magnet and H is the external magnetic field

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I and M only
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M and H only
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I and H only
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I, M and H only

The error in measuring the current with a tangent galvanometer is minimum when the deflection is about

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0°
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30°
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45°
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60°

The time period of a thin bar magnet in earth\'s magnetic field is T. If the magnet is cut into two equal parts perpendicular to its length, the time period of each part in the same field will be

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T
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2T

A tangent galvanometer is connected directly to an ideal battery. If the number of turns in the coil is doubled, the deflection will

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Increase
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Decrease
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Remain unchanged
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Either increase or decrease

Relative permittivity and permeability of a material are ɛ_r and µ_r, respectively. Which of the following value of these quantities are allowed for a diamagnetic material

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ɛr = 1.5, µr = 0.5
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ɛr = 0.5, µr = 0.5
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ɛr = 1.5, µr = 1.5
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ɛr = 0.5, µr = 1.5

Which of the following is most suitable for the core of electromagnets

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Soft iron
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Steel
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Copper-nickel alloy
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Air

Demagnetisation of magnets can be done by

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Rough handing
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Heating
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Magnetising in the opposite direction
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All of the above

Which one of the following characteristics is not associated with a ferromagnetic material

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It is strongly attracted by a magnet
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It tends to move from a region of strong magnetic field to a region of weak magnetic field
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Its origin is the spin of electrons
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Above the Curie temperature, it exhibits paramagnetic properties

If a diamagnetic substance is brought near north or south pole of a bar magnet, it is

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Attracted by the poles
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Repelled by the poles
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Repelled by the north poles and attracted by the south pole
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Attracted by the north pole and repelled by the south pole

The permanent magnet is made from which one of the following substances

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Diamagnetic
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Paramagnetic
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Ferromagnetic
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Electromagnetic

A paramagnetic substance of susceptibility 3 × 10^–4 is placed in a magnetic field of 4 × 10^–4 Am^–1. Then the intensity of magnetization in the units of Am^–1 is