MCQ Questions for Class 12 Medical Physics Magnetism And Matter Quiz 10

What is the phenomenon shown by ferromagnetic substances whereby the magnetic flux through the medium on magnetising field as well as previous state of the substance?

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Irradiation
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Hysteresis
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Inversion
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Magnetostriction

A substance is placed in a non uniform magnetic field. It experiences weak force towards the strong field. The substance is _________ type.

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Ferromagnetic
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Diamagnetic
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Paramagnetic
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None of these

Dynamo is a device that converts.

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Alternating current into direct current
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Electrical energy into mechanical energy
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Mechanical energy into electrical energy
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Heat energy into electrical energy

What is not true about paramagnetic substances?

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When freely suspended in a uniform magnetic field, they align themselves parallel to the magnetic field
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The magnetic susceptibility of paramagnetic substances has a small negative value
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Para-magnetism is temperature dependent
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They are feebly attracted by a magnet

Two equations are given below:
(A)

$\oint { \overline { E } .d\overline { A } =\cfrac { Q }{ { \in }_{ 0 } } } \quad$ ; (B)

$\quad \oint { \overline { B } .d\overline { A } } =0$
They are

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(A)-Ampere's law; (B)- Guass law for electricity
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(A)- Gauss law for electric fields; (B)- Gauss law for magnetic fields
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(A)- Faraday law; (B)- Gauss law for electric fields
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Both (A) and (B) represent Faraday law

The primary origin of magnetism lies in the

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atomic current and intrinsic spin of electrons.
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polar and non polar nature of molecules.
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pauli exclusion principle.
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electronegative nature of materials

$B_E$ represents equatorial magnetic field and

$B_A$ represents axial magnetic field due to a bar magnet. Which of the following relationships between

$B_E$ and

$B_A$ is correct?

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$B_E = 2 B_A$
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$B_A = 2 B_E$
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$B_E = 4 B_A$
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$B_A = 4 B_E$

Explanation

As equatorial magnetic field due to bar magnet is

$B_E = \dfrac{\mu_0 m}{4 \pi^3}$ .....(i)
and axial magnetic field due to bar magnet is

$B_A = \dfrac{\mu_0}{4 \pi} \dfrac{2m}{r^3}$ .... (ii)

From (i) and (ii), we get

$B_A$ =

$2B_E$

If you made a map of magnetic field lines at Melbourne in Australia, then the magnetic field lines seem to be

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go into the ground
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come out of the ground
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maintain a spiral path on the surface of earth
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move on helical path above the surface of ground

The equatorial magnetic field of earth is

$0.4$ G. Then its dipole moment on equator is

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$1.05 \times 10^{23} A m^2$
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$2.05 \times 10^{23} A m^2$
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$1.05 \times 10^{21} A m^2$
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$2.05 \times 10^{21} A m^2$

Explanation

Assuming the Earth's magnetic field is due to a bar magnet at center of the Earth, held along the polar axis of Earth, the equatorial magnetic field of Earth is given by

$B=\dfrac{\mu_0 M}{4\pi r^3}$

where,

$r=$ Radius of earth

$=6400\ km=6.4\times 10^6\ m$

$M=$ Earth's magnetic dipole moment

Given

$B= 0.4\ G= 0.4\times 10^{-4}\ T$

$\therefore M=\dfrac{Br^3}{\dfrac{\mu_o}{4\pi}}= \dfrac{(0.4\times 10^{-4})(6.4\times 10^6)^3}{10^{-7}}$

$\therefore M=1.05 \times 10^{23} Am^2$

So, option

$A$ is correct

Which of the following is correct about magnetic monopole?

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Magnetic monopole exist
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Magnetic monopole does not exist
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Magnetic monopole have constant value of monopole momentum
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The monopole momentum increase due to increase at its distance from the field.

A ball of superconducting material is dipped in liquid nitrogen and placed near a bar magnet. In which direction will it move then?

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Away from bar magnet
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Towards the bar magnet
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Around the bar magnet
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Remains constant.

The strength of the earth's magnetic field is

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constant everywhere
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zero everywhere
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having very high value
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vary from place to place on the earths surface

Explanation

The strength of the earth magnetic field is not constant. It varies from one place to other place on the surface of earth. Its value being of the order of

$10^{-5}$ T.

The earth's field departs from its dipole shape substantially at large distance (greater than about

$3000$ km). The responsible factor for this distortion is then

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motion of ions in earth's ionosphere
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motion of ions in earth's atmosphere
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motion of ions in earth's lithosphere
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motion of ions in the space.

Which of the following is universal magnetic property.?

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Ferromagnetism
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Diamagnetism
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Paramagnetism
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Anti-ferromagnetism.

The correct M-H curve for a paramagnetic material at a constant temperature (T) is represented then by

Explanation

Since intensity of magnetisation (M) of a paramagnetic material is given by

$M = C \dfrac{B}{T} = C \mu_0 \dfrac{H}{T} as \dfrac{C \mu_0}{T}$ is constant.
Then

$M \propto H$
Hence, the M-H curve will be straight line with the slope

$C \mu_0 \dfrac{1}{T}$ .

Mark the correct set of ferromagnetic substances,

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iron, cobalt and nickel
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iron, copper and lead
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silicon, bismuth and nickel
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aluminium, sodium and copper.

The temperature of transition from ferromagnetic property to paramagnetic property is called as:

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Transition temperature
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Critical temperature
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Curie temperature
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Triplet temperature

Explanation

Curie Temperature

$(T_{c})$

Which of the following property shows the property of ferromagnetic substances?

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The ferromagnetic property depends on temperature.
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The ferromagnetic property does not depend on temperature.
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At high enough temperature ferromagnet becomes a diamagnet
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At low temperature ferromagnet becomes a paramagnet

Explanation

Ferromagnetic material depends on temperature as for

$T<T_{c}(Curie's Temperature)$ it acts as a ferromagnet.

$T>T_{c}$ acts as a paramagnet.

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show the

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anti ferromagnetism
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no magnetic property
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diamagnetism
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paramagnetism

Explanation

Correct Option is D.

Explanation for the correct answer:

$\bullet$ Curie Temperature is that temperature above which there is sharp change in magnetic properties of all the magnetic substances all. All the Ferromagnetic Material becomes Paramagnetic Material above Curie Temperature.

$\bullet$ Thus, if a temperature of Nickel which is a Ferromagnetic Material is increased above Curie Temperature, then it becomes Paramagnetic.

This, Nickel will show Paramagnetic behavior above Curie Temperature. Option D is correct.

Out of given paramagnetic substance (Calcium, Chromium, Oxygen and Tungsten) which substance has maximum susceptibility?

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Calcium
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Chromium
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Oxygen
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Tungsten

Explanation

Susceptibility at the standard temperature,

$T=300K$

Calcium

$\rightarrow 1.9\times 10^{-5}$

Chromium

$\rightarrow 2.7\times 10^{-4}$

Oxygen

$\rightarrow 2.1\times 10^{-6}$

Tungsten

$\rightarrow 6.8\times 10^{-5}$

Chromium have maximum susceptibility.

The correct option is B.

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 is

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goes down
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rises up
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remains same
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first goes down and then rise

Point out the wrong statement about the magnetic properties of soft iron and steel

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Retentivity of soft iron is more than retentivity of steel.
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Coercivity of soft iron is less than coercivity of steel.
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Area of B-H loop in soft iron is smaller than the area of B-H loop for steel
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Area of B-H loop in soft iron is greater than the area of B-H loop for steel

A domain in ferromagnetic iron is in the form of a cube of side length 2

$\mu$ m then the number of iron atoms in the domain are (Molecular mass of iron =

$55 g mol^{-1}$ and density =

$7.92 g cm^{-3}$ ), maximum value of magnetisation of the given domain is (Dipole moment of an iton atom

$9.27 \times 10^{-24}A m^2)$

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$8.0 \times 10^5 A m^{-1}$
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$6.0 \times 10^4 A m^{-1}$
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$8.0 \times 10^3 A m^{-1}$
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$6.0 \times 10^3 A m^{-1}$

Explanation

Net dipole moment,

$M_N = N \times m = 6.92 \times 10^{11} \times 9.27 \times 10^{-24} = 6.4 \times 10^{-12} Am^2$
Net magnetisation =

$\dfrac{6.4 \times 10^{-12}}{8 \times 10^{-18}} = 8 \times 10^5 A m^{-1}$

The magnetic susceptibility of a paramagnetic material at

$-73^0$ is

$0.0075$ , its value at

$-173^0$ C will be

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$0.0045$
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$0.0030$
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$0.015$
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$0.0075$

Explanation

Given,

$X=0.0075 \,\,at\,\,\, T=-73^{\circ}$

Curie's law,

$X=\cfrac{C}{T}$

$X_{1} \propto \cfrac{1}{T_{1}}$

$\therefore \cfrac{X_{1}}{X_{2}}=\cfrac{T_{2}}{T_{1}}$

$X_{2}=X_{1}\times \cfrac{T_{1}}{T_{2}}=0.0075\times \cfrac{273-73}{2.73-173}=0.015$

Assertion : Paramagnetic substances get weakly attracted to a magnet.
Reason : They have tendency to move from a region of strong magnetic field to weak magnetic field

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If both assertion and reason are true and reason is the correct explanation of assertion.
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If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false

Permanent magnets are the substances having the property of

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ferromagnetism at room temperature for a long period of time.
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paramagnetism at room temperature for a long period of time.
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antiferromagnetism at room temperature for a long period of time.
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diamagnetism at room temperature for a long period of time.

The hysteresis cycle for the material of a transformer core is:

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short and wide
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tall and narrow.
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tall and wide
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short and narrow

Identify the mismatched pair.

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Hard magnet - Alnico
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Soft magnet - Soft iron
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Bar magnet - permanent magnet
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Electromagnet - Loud speaker

Explanation

Hard magnet is realized by materials of

$Al, Ni$ &

$Co$ .

Soft magnet is realized by materials of soft iron.

Bar magnet is realized by materials of Equivalent solenoid.

But Electromagnet is used in loud speaker.

Core of electromagnets are made of ferromagnetic material which have

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low permeability and low retentivity
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high permeability and high retentivity
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high permeability and low retentivity
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low permeability and high retentivity

Some equipotential surfaces of the magnetic scalar potential are shown in figure.Magnetic field at a point in the region is

0%
$10^{-4}$ T
0%
$0.5 \times 10^{-4}$ T
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$2 \times 10^{-4}$ T
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None of these

Explanation

As is clear from figure

$\triangle V = (0.2 - 0.1) 10^{-4} Tm$

$\triangle x = x sin 30^0 = 0.1 \times \dfrac{1}{2}$

$\therefore |B| = \dfrac{\triangle V}{\triangle x} = \dfrac{0.1 \times 10^{-4}}{0.1 /2} = 2 \times 10^{-4}T$

The earth's magnetic field lines resemble that of a dipole at the centre of the earth. if the magnetic moment of this dipole is close to

$8\times 10^{22}\ Am^{2}$ , the value of earth's magnetic field near the equator is close to (radius of the earth

$=6.4\times 10^{6}\ m$ )

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$0.6$ Gauss
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$1.2$ Gauss
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$1.8$ Gauss
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$0.32$ Gauss

Assertion : When diamagnetic material is placed in a non-uniform magnetic field, it tends to move from stronger to the weaker part of the magnetic field.
Reason : Diamagnetic materials possess strong magnetism.

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If both assertion and reason are true and reason is the correct explanation of assertion.
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If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false.

Assertion : Gauss's law of magnetism is different from that for electrostatics.
Reason : Isolated magnetic poles are not known to exist.

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If both assertion and reason are true and reason is the correct explanation of assertion.
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If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false.

Assertion : In water, value of magnetic field decreases.
Reason : Water is a diamagnetic substance.

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If both assertion and reason are true and reason is the correct explanation of assertion.
0%
If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false.

Explanation

Water is a diamagnetic substance. The relative permeability of water is less than

$1$ .

Assertion : When a bar magnet is freely suspended it points in the north - south direction.
Reason : The earth behaves as a magnet with the magnetic field pointing approximately from the geographic south to north

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If both assertion and reason are true and reason is the correct explanation of assertion.
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If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false

If a magnetic material is having magnetic susceptibility

$(\chi)=-1$ , then the relative magnetic permeability

$(\mu_r)$ and type of magnetic material is?

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$0$ , diamagnetic
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$2$ , ferromagnetic
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$1$ , paramagnetic
0%
$-1$ , diamagnetic

Explanation

Here,

$\chi =-1$
then

$\mu_r=1+\chi \Rightarrow \mu_r=1+(-1)=I-1=0$
Since, magnetic susceptibility of given material is less than one. Hence, the given magnetic material is a diamagnetic material.

Assertion : Substances which at room temperature retain their ferromagnetic property for a long period of time are called permanent magnets.
Reason : Permanent magnet can be made by placing a ferromagnetic rod in a solenoid and passing current through it.

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If both assertion and reason are true and reason is the correct explanation of assertion.
0%
If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
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If both assertion and reason are false.

Assertion : The product of magnetic susceptibility and absolute temperature for a paramagnetic substance is constant.
Reason : Susceptibility is positive but very small for paramagnetic substance.

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If both assertion and reason are true and reason is the correct explanation of assertion.
0%
If both assertion and reason are true and reason is not the correct explanation of assertion.
0%
If assertion is true but reason is false.
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If both assertion and reason are false

Explanation

The susceptibility of a paramagnetic substance is inversely proportional to absolute temperature.

$X \propto \frac{1}{T}$
Hence

$XT = constant$
Also for paramagnetic substances the susceptibility is positive and very small.

Assertion : At high temperature, a ferromagnet becomes a paramagnet.
Reason : The ferromagnetic property depends on temperature.

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If both assertion and reason are true and reason is the correct explanation of assertion.
0%
If both assertion and reason are true and reason is not the correct explanation of assertion.
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If assertion is true but reason is false.
0%
If both assertion and reason are false.

Which of the following is universal magnetic property?

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Ferromagnetism
0%
Diamagnetism
0%
Para magnetism
0%
Anti-ferromagnetism

A ball of superconducting material is dipped in liquid nitrogen and placed near a bar magnet. In which direction will it move?

0%
Away from bar magnet
0%
Towards the bar magnet
0%
Around the bar magnet
0%
Remain constant

Point out the correct set of diamagnetic substances.

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Aluminium, sodium calcium and oxygen
0%
Bismuth, copper, lead and silicon
0%
Cobalt, nickel, gadolinium and aluminium
0%
Silver, niobium, magnesium and calcium

Explanation

Bismuth, copper, lead, and silicon all are having the diamagnetic property as atoms of these materials have resultant magnetic moment zero.
Hence, the correct option is

$(B)$

Consider the two idealised systems.
(i) a parallel plate capacitor with large plates and small separation and
(ii) a long solenoid of length L

$> >$ R, radius of cross-section.
In (i)

$\vec{E}$ is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as given.

0%
Case (i) contradicts Gauss's law for electrostatic fields
0%
Case (ii) contradicts Gauss's law for magnetic fields
0%
Case (i) agree with $\oint \vec{E}\cdot \vec{dl}=0$
0%
Case (ii) contradicts $\oint \vec{H}\cdot \vec{dl}=I_{en}$

Explanation

We know that the Electric field lines do not form a closed loop whereas the magnetic field lines form constant closed loop.

The Gauss' law for electrostatics states that:

$\int E.dl=\dfrac{Q}{\varepsilon_0}$

And the Gauss' law for magnetic field states that:

$\int B.ds=0$

It means that the number of the magnetic field lines entering the closed surface is same as the number of lines exiting the surface. this contradicts the second case.

Option

$(B)$ is correct.

Some equipotential surfaces of the magnetic scalar potential are shown in figure. Magnetic field at a point in the region is:

0%
$10^{-4}$ T
0%
$0.5\times 10^{-4}$ T
0%
$2\times 10^{-4}$ T
0%
None of these

Explanation

As is clear from figure

$\Delta V=(0.2-0.1)10^{-4}Tm$

$\Delta x=x\sin 30^o=0.1\times \dfrac{1}{2}$

$\therefore |B|=\dfrac{\Delta V}{\Delta x}=\dfrac{0.1\times 10^{-4}}{0.1/2}=2\times 10^{-4}T$ .
1123828_951075_ans_34cc4920061f488e8006e1bc4971a87a.png

Core of electromagnets are made of ferromagnetic materials which have.

0%
Low permeability and low retentivity
0%
High permeability and high retentivity
0%
High permeability and low retentivity
0%
Low permeability and high retentivity

In a permanent magnet at room temperature.

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Magnetic moment of each molecule is zero
0%
The individual molecules have non-zero magnetic moment which are all perfectly aligned
0%
Domains are partially aligned
0%
Domains are all perfectly aligned

Permanent magnets are the substances having the property of.

0%
Ferromagnetism at room temperature for a long period of time
0%
Paramagnetism at room temperature for a long period of time
0%
Anti ferromagnetism at room temperature for a long period of time
0%
Diamagnetism at room temperature for a long period of time

Mark the correct set of ferromagnetic substances.

0%
Iron, cobalt and nickel
0%
Iron, copper and lead
0%
Silicon, bismuth and nickel
0%
Aluminium, sodium and copper

Short Answer Type Question.
Which magnetic property is present in all substances?

0%
Diamagnetism
0%
massless
0%
frictionless
0%
no common property

In the region closer to the oscillating charges, the phase difference between

$\overrightarrow { E }$ and

$\overrightarrow { B }$ fields is _____ and their magnitude quickly decreases as _____ with distance

$r$ from the source.

0%
$0,{ r }^{ -1 }$
0%
$\cfrac { \pi }{ 2 } ,{ r }^{ -1 }$
0%
$\cfrac { \pi }{ 2 } ,{ r }^{ -3 }$
0%
$0,{ r }^{ -3 }$

CBSE Questions for Class 12 Medical Physics Magnetism And Matter Quiz 10 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

CBSE Questions for Class 12 Medical Physics Magnetism And Matter Quiz 10 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

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