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

Ratio of magnetic intensities for an axial point and a point on broad side- on position at equal distance d from the centre of magnet will be $$or$$ The magnetic field at a distance d from a short bar magnet in longitudinal and transverse  positions are in the ratio
  • $$1:1$$
  • $$1:6$$
  • $$2:1$$
  • $$3:2$$
For substances hysteresis (B-H) curves are given as shown in figure. For making temporary magnet which of the following is best
An isolated unit north pole expending force of $$2\times { 10 }^{ -7 }N$$ when kept at a distance 1m from a magnetic pole in air. The strength of thr pole is:
  • $$2\times { 10 }^{ 7 }A-m$$
  • $$2A-m$$
  • $$2\times { 10 }^{ -11 }A-m$$
  • $$4Am$$
An electron of kinetic energy of $$7.2\times { 10 }^{ -18 }J$$ is revolving on circular path in magnetic field $$9\times { 10 }^{ -5 }Wb/{ m }^{ 2 }$$ then radius of its circular path is :-
  • 1.25 cm
  • 2.5 m
  • 25 cm
  • 25.0 cm
Which of the following statements regarding magnetic lines of force is correct?
  • Total magnetic flux linked with a closed surface is always zero
  • They need not be perpendicular to the surface from where they start of whre they meet
  • They may or may not pass through a conductor
  • All of these
The $$\chi-(\dfrac{1}{T})$$ graph for an alloy of paramagnetic nature is shown in figure. The curie constant is, then
1348891_24a3bc8527064b7ca3cb9d689681bc08.png
  • $$57\ K$$
  • $$2.8 \times 10^{-3} K$$
  • $$570\ K$$
  • $$17.5 \times 10^{-3} K$$
The susceptibility of a diamagnetic material is
  • directly proportional to $$T$$
  • inversely proportional to $$T $$
  • independent of $$\mathrm { T } $$
  • inversely proportional to $$\mathrm { T } ^ { 2 }$$
A bar magnet is demagnetized by inserting it inside a solenoid of length $$0.2m, 100turas$$, and carrying a current of $$5.2A$$. The coercivity of the bar magnet is:
  • $$1200\, A/m$$
  • $$2600\, A/m$$
  • $$5200\, A/jm$$
  • $$285\, A/m$$
Consider the following statements and select the options which are correct.
  • Iron loses its magnetism easily.
  • Steel is a hard magnetic material.
  • Soft iron is used to make permanent magnet.
  • None of these
A metallic rod of mass per unit length 0.5 kg $$m ^ { - 1 }$$ is lying horizontally on a smooth inclined plane which makes an angle of $${ 30 }^{ \circ  }$$ with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is
  • $$14.76 \mathrm { A }$$
  • $$5.98 \mathrm { A }$$
  • $$7.14 \mathrm { A }$$
  • $$11.3 \mathrm { A }$$
What happens to the force between magnetic poles when their pole strength and the distance between them are both doubled
  • Force increases to two times the previous value
  • No change
  • Force decreases to half-the previous value
  • Force increases to four times the previous value
According to  molecular orbital theory, the paramagnetism of $$O_{2}$$  molecule is due to presence of 
  • Unpaired electrons in the bonding $$\sigma $$ molecular orbital
  • Unpaired electrons in the anti- bonding $$\sigma $$ molecular orbital
  • Unpaired electron in the bonding $$\pi $$ molecular orbital
  • Unpaired electrons in the anti - bonding $$\pi $$ molecular obrital
Mark out the correct options.
  • diamagnetism occurs in all materials.
  • diamagnetism results from the partial alignment of permanent magnetic moment.
  • the magnetizing field intensity H is always zero in free space .
  • the magnetic field of unduced magnetic moment is opposite to the applied field.
A point P is situated on the equator of short magnetic dipole of moment of 2 $$Am^2$$. If the distance of that point from its center is 10 cm the magnetic potential at point P will be:
  • $$4 \times 10^{-5} J/Am$$
  • $$3.5 \times 10^{-3} J/Am$$
  • $$1.55 \times 10^{-6} J/Am$$
  • zero
The earth's magnetic field at the equator is approximately 0.4$$G$$. Estimate the Earth's dipole moment.
  • $$1.05 \times 10 ^ { 23 } \mathrm { Am } ^ { 2 }$$
  • $$1.05 \times 10 ^ { - 23 } \mathrm { Am } ^ { 2 }$$
  • $$5.01 \times 10 ^ { 23 } \mathrm { Am } ^ { 2 }$$
  • $$5.01 \times 10 ^ { - 23 } \mathrm { Am } ^ { 2 }$$
A coil of area 10 $$\mathrm { cm } ^ { 2 }$$ and 10 turns is in magnetic field directed perpendicular to the plane and changing at a rate of $$10 ^ { 8 }$$ gauss /s  The resistance of coil is 20 $$\Omega$$ . The current in the coil will be
  • 0.5 A
  • $$5 \times 10 ^ { - 3 } \mathrm { A }$$
  • 0.05 A
  • 5 A
Magnetic dipole moment is a vector quantity directed from:-
  • south to North pole
  • North to south pole
  • East to West direction
  • West to East direction
Density of iron is 7.8 g/cc and induced magnetic field in iron is 1 tesla then find magnetic dipole moment of each iron atom.
  • $$57 \times 10^{-24} Am^2$$
  • $$9.5 \times 10^{-24} Am^2$$
  • $$21 \times 10^{-24} Am^2$$
  • $$37 \times 10^{-24} Am^2$$
The mass of a specimen of a ferromagnetic material is  $$0.6 kg$$  and its density is  $$7.8\times 10^{ { 3 } }{ kg }/{ m }^{ { 3 } }.$$  If the area of hysteresis loop of alternating magnetising field of frequency  $$50 { Hz }$$  is  $$0.722{ MKS }$$  units then the hysteresis loss per second will be :-
  • $$277.7\times 10^{ { -5 } }{ J }/{ sec }$$
  • $$277.7\times 10^{ { -6 } }{ J }/{ sec }$$
  • $$277.7\times 10^{ { -4 } }{ J }/{ sec }$$
  • $$277.7\times 10^{ { -3 } }{ J }/{ sec }$$
A straight conductor carrying a current is kept in a uniform magnetic field so as to experience maximum force. If now the conductor is turned in its own plane such that the force acting on it is half of the maximum force, then the angle made by the conductor in the final position with respect to the field is
  • $$
    60^{\circ}
    $$
  • $$
    45^{\circ}
    $$
  • $$
    30^{\circ}
    $$
  • $$
    90^{\circ}
    $$
 If a magnet of pole strength m is divided into 2n equal parts by dissecting along lines parallel to length, then pole strength of each segment will be
  • same as m
  • $$\dfrac { m } { n }$$
  • $$\dfrac { m } { 2 n }$$
  • $$\dfrac { 2 m } { n }$$
Which of the following is paramagnetic  in nature ? 
  • $$N_{2}$$
  • $$C_{2}$$
  • $$B_{2}$$
  • $$O_{2}^{2+}$$
 For a magnetic material graph between intensity of magnetisation $$( \vec { I } )$$ and magnetic intensity $$( \vec { H } )$$  is as shown in diagram
Then material is 
1442672_0ec1bff013424dd6ab78400b17d27b8a.png
  • Diamagnetic
  • Paramagnetic
  • Feromagnetic
  • All
A magnetic needle of magnetic moment $$6.7\times{10}^{-2}A{m}^{2}$$ and moment of inertia $$7.5\times{10}^{-6}kg{m}^{2}$$ is performing simple harmonic oscillations in a magnetic field of $$0.01T$$. Time taken for $$10$$ complete oscillations is
  • $$8.76s$$
  • $$6.65s$$
  • $$8.89s$$
  • $$6.98s$$
Permanent magnets are always ___________ types of magnetic materials.
  • Diamagnetic
  • Paramagnetic
  • Ferromagnetic
  • Ferrimagnetic
Magnetic field intensity is defined as 
  • Magnetic moment per unit volume
  • Magnetic induction force acting on a unit magnetic pole
  • Number of lines of force crossing per unit area
  • Number of lines of force crossing unit Volume.
Out of the following, identity the material which can be classified as diamagnetic
  • Aluminium
  • Bismuth
  • Copper
  • sodium
A coil in the shape of an equilateral triangle of side I is suspended between the pole pieces of a permanent magnet, such that $$ \overrightarrow { B }  $$ is in plane of the coil.If due to a current I in the triangle,a torque $$ \overrightarrow { T }  $$  acts on it,then the side I of the triangle is
  • $$ \frac { 2 }{ \sqrt { 3 } } \frac { T }{ BI } $$
  • $$ 2\left[ \frac { T }{ \sqrt { 3 } BI } \right]^{1/2} $$
  • $$ \frac { 2 }{ \sqrt { 3 } } \left[ \frac { T }{ BI } \right]^{1/2} $$
  • $$ \frac { 1 }{ \sqrt { 3 } } \left[ \frac { T }{ BI } \right] $$
Force between two identical short bar magnets whose centres are $$ r$$ metre apart is $$4.8 N$$ when their axes are in the same line. If the separation is increased to $$2r$$ metre, the force between them is reduced to 
  • $$0.3N$$
  • $$0.6N$$
  • $$24N$$
  • $$1.2$$
The ends of three metal rods are tested by holding end $$Q$$ of rod $$1$$ close to the others in turn.
The results are as follows.
End $$Q$$ attracts end $$R$$.
End $$Q$$ attracts end $$S$$.
End $$Q$$ attracts end $$T$$.
End $$Q$$ repels end $$U$$.
Which of the metal rods is a magnet?

1643445_984fe93906d345ed8e13a981533e43c6.png
  • Rod $$1$$ only
  • Rod $$1$$ and rod $$2$$
  • Rod $$1$$ and rod $$3$$
  • Rod $$3$$ only
A galvanometer of number of turns $$175$$, having $$1 \,cm^2$$ area, turns through $$1^o$$ when a current of $$1mA$$ is passed. Find magnetic field if torsional constant of spring is $$10^{-6} N - m$$
  • $$10^{-4} T$$
  • $$10^{-3} T$$
  • $$10^{-5} T$$
  • $$10^{-2} T$$
The dimensions of the ratio of magnetic flux $$(\phi)$$ and permeability $$(\mu)$$ are?
  • $$[M^0L^1T^0A^1]$$
  • $$[M^0L^{-3}T^0A^1]$$
  • $$[M^0L^1T^1A^{-1}]$$
  • $$[M^0L^2T^0A^1]$$
Which diagram shows the magnetic field around a bar magnet?
Needles $$N_1, N_2$$ and $$N_3$$ are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will?
  • Attract all three of them
  • Attract $$N_1$$ strongly, $$N_2$$ weakly and repel $$N_3$$ weakly
  • Attract $$N_1$$ strongly but repel $$N_2$$ and $$N_3$$ weakly
  • Attract $$N_1$$ and $$N_2$$ strongly but repel $$N_3$$
Two magnetic dipoles are lying as shown in figure. the separation '$$d$$' between them is very large. A point charge $$Q$$ is projected with some speed $$v$$ as shown. The force experienced by the charged particle is:
1611193_19fdc3b9ca71405aa3ae1b122d8d242d.png
  • $$0$$
  • $$\dfrac{4\sqrt{2}\mu_0 MQv}{\pi d^3}$$
  • $$\dfrac{\sqrt{2}\mu_0 MQv}{\pi d^3}$$
  • $$\dfrac{2\surd{2}\mu_0 MQv}{\pi d^3}$$
A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is $$E = 6\ Vm^{-1}$$ along y-direction. Its corresponding magnetic field component, $$B$$ would be
  • $$6\times 10^{-8}T$$ along z-direction
  • $$6\times 10^{-8}T$$ along x-direction
  • $$2\times 10^{-8}T$$ along z-direction
  • $$2\times 10^{-8}T$$ along y-direction
A jet plane having a wing-span of $$25$$ m is travelling horizontally towards east with a speed of $$3600$$ km/hour. If the Earth's magnetic field at the location is $$4\times 10^{-4}$$T and the angle of dip is $$30^o$$, then, the potential difference between the ends of the wing is?
  • $$4$$ V
  • $$5$$ V
  • $$2$$ V
  • $$2.5$$ V
Six similar magnetic poles are placed on six corners of a regular hexagon of side $$10\ cm$$. A south pole of strength $$10\ Am$$ is placed at the centre of hexagon. The magnetic force on the south pole is :
  • zero
  • $$4\pi \times 10^{-4}\ N$$
  • $$10\ N$$
  • $$none\ of\ these$$
Which one of the following is a vector quantity ?
  • Pole strength
  • Permeability
  • Magnetic lines of forces
  • Magnetic pole
Mark correct option or options :
  • Electric field and magnetic field are basically independent
  • Electric field and magnetic field are two aspect of the electromagnetic field
  • Electric field and magnetic field may be produced by charge in rest
  • Both $$(a)$$ and $$(c)$$ are correct
Three similar magnetic south poles each of strength $$10\ Am$$ are placed at the corners of an equilateral triangle of side $$20\ cm$$. The magnetic force on one of the pole is :
  • $$0.25\times 10^{-3}\ N$$
  • $$10^{-3}\ N$$
  • $$10\times 10^{-3}\ N$$
  • $$none\ of\ these$$
If the distance between two similar magnetic poles held one $$cm$$ apart be doubled, then the force of interaction between them will be :
  • doubled
  • halved
  • unchanged
  • one quarter of the original value
The only property possessed by ferromagnetic substance is
  • Hysteresis
  • Susceptibility
  • Directional property
  • Attracting magnetic substances
Which of the following is correct representation of magnetic lines of force ?
  • None of the above
Curies temperature is the temperature above which :
  • a paramagnetic material becomes ferromagnetic
  • a ferromagnetic material becomes paramagnetic
  • a paramagnetic material becomes diamagnetic
  • a ferromagnetic material becomes diamagnetic
An atom is paramagnetic if it has :
  • an electric dipole moment
  • no magnetic moment
  • a magnetic moment
  • no electric dipole moment
A metal sheet is placed in front of a strong magnetic pole. A force is needed to Neglect any effect of paramagnetism, diamagnetism and gravity.
  • hold the sheet there if the metal is magnetic
  • hold the sheet there if the metal is nonmagnetic
  • move the sheet away from the pole with uniform velocity if the metal is magnetic
  • move the sheet away from the pole with uniform velocity if the metal is nonmagnetic
The diagram shows the magnetic field around two bar magnets. Which diagram shows the poles of the magnets?
1647128_3f67293106cd48d7b45f961c6ca1c0e3.png
When a ferromagnetic material goes through a hysteresis loop, the magnetic susceptibility.
  • has a fixed value
  • may be zero
  • may be infinity
  • may be negative.
The permanent magnetic moment of the atoms of a material is not zero. The material.
  • must be paramagnetic
  • must be diamagnetic
  • must be ferromagnetic
  • may be paramagnetic.
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Physics Quiz Questions and Answers