Physics - Magnetism Matter - Quiz-2

A line passing through places having zero value of magnetic dip is called

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Isoclinic line
(2) Agonic line
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2
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Isogonic line
(4) Aclinic line
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4

The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is

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$\tan^{- 1} (\frac{3}{4})$
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$\sin^{- 1} (\frac{3}{4})$
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$\tan^{- 1} (\frac{4}{3})$
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$\sin^{- 1} (\frac{3}{5})$

At a certain place, the horizontal component B₀ and the vertical component V₀ of the earth's magnetic field are equal in magnitude. The total intensity at the place will be

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$B_{0}$
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$B_{0}^{2}$
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$2 B_{0}$
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$\sqrt{2} B_{0}$

Two bar magnets with magnetic moments 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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() $θ = \tan^{- 1} (\frac{1}{\sqrt{3}})$
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() $θ = \tan^{- 1} (\sqrt{3})$
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() $θ = \tan^{- 1} (\frac{1}{2})$
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() $θ = \tan^{- 1} (\frac{3}{4})$

The angle of dip at a certain place is 30^o. If the horizontal component of the earth’s magnetic field is H, the intensity of the total magnetic field is

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$\frac{H}{2}$
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$\frac{2 H}{\sqrt{3}}$
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$H \sqrt{2}$
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$H \sqrt{3}$

The time period of oscillation of a freely suspended bar magnet with usual notations is given by

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$T = 2 π \sqrt{\frac{I}{{MB}_{H}}}$
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$T = 2 π \sqrt{\frac{M B_{H}}{I}}$
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$T = 2 \sqrt{\frac{I}{{MB}_{H}}}$
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$T = 2 π \sqrt{\frac{B_{H}}{M I}}$

Time period for a magnet is T. If it is divided in four equal parts along its axis and perpendicular to its axis as shown then time period for each part will be

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T/4
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4T
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T/2
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T

The period of oscillation of a magnet in vibration magnetometer is 2 sec. The period of oscillation of a magnet whose magnetic moment is four times that of the first magnet is

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1 sec
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4 sec
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8 sec
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0.5 sec

A magnetic needle is made to vibrate in uniform field H, then its time period is T. If it vibrates in the field of intensity 4H, its time period will be:

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2T
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T/2
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2/T
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T

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^o and 15 oscillations per minute at a place where dip angle is 60^o. The ratio of total earth's magnetic field at the two places is:

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$3 \sqrt{3} : 8$
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$16 : 9 \sqrt{3}$
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4:9
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$2 \sqrt{3} : 9$

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

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$\frac{n}{2 \sqrt{2}}$
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$\frac{n}{\sqrt{2}}$
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$2 \sqrt{2} n$
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$\sqrt{2} n$

Magnets A and B are geometrically similar but the magnetic moment of A is twice that of B. If T₁and T₂ be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then $\frac{T_{1}}{T_{2}}$ will be:

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1/3
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1/2
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$\frac{1}{\sqrt{3}}$
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$\sqrt{3}$

The time period of oscillation of a bar magnet suspended horizontally along the magnetic meridian is T₀. If this magnet is replaced by another magnet of the same size and pole strength but with double the mass, the new time period will be

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$\frac{T_{0}}{2}$
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$\frac{T_{0}}{\sqrt{2}}$
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$\sqrt{2} T_{0}$
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2T₀

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

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Increase by 19%
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Decrease by 19%
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Increase by 11%
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Decrease by 21%

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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1/4
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$\frac{1}{2 \sqrt{2}}$
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1/2
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2

Two identical short bar magnets, each having magnetic moment M, are placed a distance of 2d apart with axes perpendicular to each other in a horizontal plane. The magnetic induction at a point midway between them is

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(a) $\frac{μ_{0}}{4 π} (\sqrt{2}) \frac{M}{d^{3}}$ (b) $\frac{μ_{0}}{4 π} (\sqrt{3}) \frac{M}{d^{3}}$
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(c) $(\frac{2 μ_{0}}{4 π}) \frac{M}{d^{3}}$ (d) $\frac{μ_{0}}{4 π} (\sqrt{5}) \frac{M}{d^{3}}$
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A superconductor exhibits perfect :

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Ferrimagnetism
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Ferromagnetism
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Paramagnetism
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Diamagnetism

Among the following properties describing diamagnetism identify the property that is wrongly stated

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Diamagnetic material do not have permanent magnetic moment
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Diamagnetism is explained in terms of electromagnetic induction
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Diamagnetic materials have a small positive susceptibility
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The magnetic moment of individual electrons neutralize each other

If a magnet is suspended at an angle 30^o to the magnetic meridian, it makes an angle of 45^owith the horizontal. The real dip is

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(a) $\tan^{- 1} (\frac{\sqrt{3}}{2})$
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() $\tan^{- 1} (\sqrt{3})$
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() $\tan^{- 1} (\sqrt{\frac{3}{2}})$
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(d) $\tan^{- 1} (\frac{2}{\sqrt{3}})$

The true value of angle of dip at a place is 60^o, the apparent dip in a plane inclined at an angle of 30^o with magnetic meridian is

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$\tan^{- 1} (\frac{1}{2})$
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$\tan^{- 1} (2)$
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$\tan^{- 1} (\frac{2}{3})$
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None of these

A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is $2^{\frac{5}{4}}$ seconds. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in seconds is :

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$2^{\frac{1}{4}}$
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$2^{\frac{1}{2}}$
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2
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$2^{\frac{3}{4}}$

A cylindrical rod magnet has a length of 5 cm and a diameter of 1 cm. It has a uniform magnetization of 5.30 × 10³Amp/m³. What is its magnetic dipole moment?

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$1 \times 10^{- 2} J / T$
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$2.08 \times 10^{- 2} J / T$
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$3.08 \times 10^{- 2} J / T$
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$1.52 \times 10^{- 2} J / T$

Two magnets of equal mass are joined at right angles to each other as shown the magnet 1 has a magnetic moment 3 times that of magnet 2. This arrangement is pivoted so that it is free to rotate in the horizontal plane. In equilibrium what angle will the magnet 1 subtend with the magnetic meridian

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$\tan^{- 1} (\frac{1}{2})$
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$\tan^{- 1} (\frac{1}{3})$
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$\tan^{- 1} (1)$
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$0 °$

Two magnets A and B are identical and these are arranged as shown in the figure. Their length is negligible in comparison to the separation between them. A magnetic needle is placed between the magnets at point P which gets deflected through an angle $θ$ under the influence of magnets. The ratio of distance d₁ and d₂ will be

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$(2 \tan θ)^{1 / 3}$
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$(2 \tan θ)^{- 1 / 3}$
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$(2 c o t θ)^{1 / 3}$
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$(2 c o t θ)^{- 1 / 3}$

Two short magnets of equal dipole moments M are fastened perpendicularly at their centres (figure). The magnitude of the magnetic field at a distance d from the centre on the bisector of the right angle is :

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$\frac{μ_{0}}{4 π} \frac{M}{d^{3}}$
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$\frac{μ_{0}}{4 π} \frac{M \sqrt{2}}{d^{3}}$
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$\frac{μ_{0}}{4 π} \frac{2 \sqrt{2} M}{d^{3}}$
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$\frac{μ_{0}}{4 π} \frac{2 M}{d^{3}}$

Two identical bar magnets with a length of 10 cm and weight 50 gm-weight are arranged

freely with their like poles facing in an inverted vertical glass tube. The upper magnet

hangs in the air above the lower one so that the distance between the nearest pole of the

magnet is 3mm. Pole strength of the poles of each magnet will be:

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6.64 amp $\times$ m
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2 amp $\times$ m
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10.25 amp $\times$ m
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None of these

Each atom of an iron bar (5 cm × 1 cm × 1 cm) has a magnetic moment $1.8 \times 10^{- 23} A m^{2}$ . Knowing that the density of iron is $7.78 \times 10^{3} k g m^{- 3}$ atomic weight is 56 and Avogadro's number is $6.02 \times 10^{23}$ the magnetic moment of the bar in the state of magnetic saturation will be:

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4.75 Am²
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5.74 Am²
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7.54 Am²
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75.4 Am²

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45^o 4. 90^o
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4
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0^o 2. 30^o
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A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 seconds. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 seconds. Then the angle of dip is

A bar magnet has coercivity $4 \times 10^{3} A m^{- 1}$ . It is desired to demagnetize it by inserting it inside a solenoid 12 cm long and having 60 turns. The current that should be sent through the solenoid is

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2 A
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4 A
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6 A
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8 A

For substances hysteresis (B - H) curves are given as shown in figure. For making temporary magnet which of the following is best.

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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