CBSE Questions for Class 12 Medical Physics Magnetism And Matter Quiz 5 - MCQExams.com

A susceptibility of a certain magnetic material isWhat is the class of the magnetic material?
  • Diamagnetic
  • Paramagnetic
  • Ferromagnetic
  • Ferroelectric
If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is :
  • Attracted by both the poles
  • Repelled by both the poles
  • Repelled by the north pole and attracted by the south pole
  • Attracted by the north pole and repelled by the south pole
State whether True or False :
Hysteresis is the number of lines of force per unit area in a magnetic field.
  • True
  • False
Which of the following is true regarding superconductivity?
  • The superconducting state cannot exist in the presence of a magnetic field lesser than a critical value, even at absolute zero
  • The superconducting state exists in the presence of a magnetic field greater than a critical value, even at absolute zero
  • The superconducting state exists in the presence of a magnetic field lesser than a critical value, even at absolute zero
  • The superconducting state cannot exist in the presence of a magnetic field greater than a critical value, even at absolute zero
Susceptibility of ferromagnetic substance is
  • $$> 1$$
  • $$< 1$$
  • zero
  • $$1$$
State whether True or False :
A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
  • True
  • False
Permanent magnets should have 
  • High retentivity and low coercivity.
  • Low retentivity and high coercivity.
  • High retentivity and high coercivity.
  • Low retentivity and low coercivity.
The inherent property of all materials is
  • Diamagnetism
  • Paramagnetism
  • Ferromagnetism
  • Both a and b
Which of the following statements given below is not true in the context of magnetic lines of force?
  • Magnetic lines of forces are closed continuous curves
  • No two magnetic lines of force can intersect each other
  • Magnetic lines of force are far away from each other at the poles
  • The start from the north pole and end on the south pole
The materials suitable for making electromagnets should have:
  • High retentivity and high coercivity
  • Low retentivity and low coercivity
  • High retentivity and low coercivity
  • Low retentivity and high coercivity
The substances which are attracted towards a magnet are called _______.
  • metals
  • ferro-magnetic materials
  • non-metals
  • dia-magnetic materials
Field which does not have magnetic poles is:
  • Straight lined
  • Normal to Wire
  • Tangent to Wire
  • Circular
Critical temperature can be defined as the
  • Temperature at which there is no motion between the molecules
  • Temperature at which a gas is converted into its liquid state
  • Temperature at which volume of a gas becomes zero
  • Temperature above which a gas cannot be liquefied no matter however high the pressure may be
Which of the following material is not ferromagnetic in nature?
  • $$Fe$$
  • $$Co$$
  • $$Ni$$
  • $$Al$$
The hysteresis cycle for the material of permanent magnet is
  • Short and wide
  • Tall and narrow
  • Tall and wide
  • Short and narrow
The susceptibility and permeability of a perfectly diamagnetic substance is
  • $$1$$ and $$0$$
  • $$0$$ and $$1$$
  • $$-1$$ and $$0$$
  • $$-1$$ and $$1$$
Identify the correctly matched pair :
  • Material - Diamagnetic Example - Gadolinium
  • Material - Soft ferromagneti Example - Alnico
  • Material - Hard ferromagneti Example - Copper
  • Material - Paramagnetic Example -Sodium
  • Material - Permanent magnet Example - Aluminium
Materials suitable for permanent magnet, must have which of the following properties?
  • High retentivity, low coercivity and high permeability
  • Low retentivity, low coercivity and low permeability
  • Low retentivity, high coercivity and low permeability
  • High retentivity, high coercivity and high permeability
Which one of the following is correct statement about magnetic forces?
  • Magnetic forces always obey Newton's third law
  • Magnetic forces do not obey Newton's third law
  • For very high current, magnetic forces obey Newton's third law
  • Inside low magnetic field, magnetic obey Newton's third law
Three identical bars $$A, B$$ and $$C$$ are made of different magnetic materials. When kept in a uniform magnetic field, the field lines around them look as follows:
Make the correspondence of these bars with their material being diamagnetic $$(D)$$, ferromagnetic $$(F)$$ and paramagnetic $$(P)$$:
1012661_1e39264c5edf4e689cb9defce8a64a0d.png
  • $$A\leftrightarrow F, B\leftrightarrow P, C\leftrightarrow D$$
  • $$A\leftrightarrow P, B\leftrightarrow F, C\leftrightarrow D$$
  • $$A\leftrightarrow D, B\leftrightarrow P, C\leftrightarrow F$$
  • $$A\leftrightarrow F, B\leftrightarrow D, C\leftrightarrow P$$
The hysteresis cycle for the material of a transformer core is?
  • Short and wide
  • Tall and narrow
  • Tall and wide
  • Short and narrow
A wire is placed between the poles of two fixed bar magnets as shown in the figure. A small current in the wire is into the plane of the paper. The direction of the magnetic force on the wire is
943007_d88d2d2409704b5794fc65947313b201.png
  • Left
  • Right
  • Up
  • Down
A charged particle enters a region of a uniform magnetic field at an angle of $$85^o$$ to the magnetic lines of force. The path of the particle is a circle.
  • True
  • False
Which of the following is not correct about the magnetic field lines?
  • The magnetic field lines of a magnet form continuous closed loops.
  • The tangent to the field line at a given point represents the direction of the net magnetic field B at that point.
  • The larger the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B.
  • The magnetic field lines may intersect to each other in certain conditions.
The electron performs circular motion of radius r, perpendicular to a uniform magnetic field B. The kinetic energy gained by this electron in half the revolution is ___________.
  • $$\dfrac{1}{2}mv^2$$
  • $$\dfrac{1}{4}mv^2$$
  • Zero
  • $$\pi rBeV$$
A constant force F is being applied on a rod of length  kept at rest on two parallel conducting rails connected at ends by resistance R in uniform kept at rest on two parallel conducting rails connected at ends by resistance R in uniform magnetic field B as shown 
1400349_86c032c572fe471e8881d51ab639905a.jpg
  • the power delivered by force will be constant with time
  • the power delivered by force will be increasing first and then will decrease
  • the rate of power delivered by the external force will be increasing continously
  • the rate of power delivered by the external force will be decreasing continously
Choose the incorrect statement from the following:
  • Magnetic lines of force never intersect
  • Magnetic lines of force emanate from north pole
  • Magnetic lines of force travel in straight lines
  • Magnetic lines of force are curved lines
Magnetic field does not interact with
  • Moving charge
  • Stationary charge
  • Any charge
  • Cannot say
Which of the following species is para-magnetic
  • A carbonium ion
  • A free radical
  • A carbonium
  • All of these
There is no change in the energy of a charged particle moving in a magnetic field although a magnetic force is acting on it.
  • True
  • False
The diagram shows two magnets and two iron rods placed in a line.
Which magnetic poles are induced at the ends $$J$$ and $$K$$ of the iron rods?

1646937_f42d231d75264ed4bfd3753afe4dbc53.png
  • Pole induced at end $$J$$ - $$N$$, pole induced at end $$K$$ - $$N$$
  • Pole induced at end $$J$$ - $$N$$, pole induced at end $$K$$ - $$S$$
  • Pole induced at end $$J$$ - $$S$$, pole induced at end $$K$$ - $$N$$
  • Pole induced at end $$J$$ - $$S$$, pole induced at end $$K$$ - $$S$$
Which metal is suitable to use to make a permanent magnet?
  • Aluminium
  • Brass
  • Iron
  • Steel
In a permanent magnet at room temperature
  • magnetic moment of each molecule is zero.
  • the individual molecules have non-zero magnetic moment which are all perfectly aligned.
  • domains are partially aligned.
  • domains are all perfectly aligned.
Assertion(A) : The ferro magnetic substances do not obey curie's law.
Reason(R) : At curie point ferromagnetic substances start behaving as a paramagnetic substances.
  • Both A, R are true and R is the correct explanation of A
  • Both A, R are true and R is not correct explanation of A
  • A is true, R is false
  • A is false R is true

A rod of a paramagnetic substance is placed in a non-uniform magnetic field. Which of the following figure shows its alignment in the field ?
If the magnetic moment of the atoms of a substance is zero, the substance is called:
  • Diamagnetic
  • Ferromagnetic
  • Paramagnetic
  • Antiferromagnetic
Assertion(A) : If one arm of a $$U-$$tube containing a diamagnetic solution is placed in between the poles of a strong magnet with the level in line with the field, the level of the solution falls
Reason(R) : Diamagnetic substances are repelled by the magnetic field
  • both A,R are true and R is the correct explanation of A
  • both A,R are true and R is not correct explanation of A
  • A is true, R is false
  • A is false R is true

The area enclosed by a hysteresis loop is a measure of
  • retentivity
  • susceptibility
  • permeability
  • energy loss per cycle

The lines of force of a bar magnet are:
  • Parallel and straight
  • Concentric circles
  • Curved lines
  • Curved closed loops

For a paramagnetic material, the dependence of the magnetic susceptibility $$\chi $$ on the absolute temperature T is given by 
  • $$\chi \alpha T$$
  • $$\chi \alpha$$ $$ constant \times T$$
  • $$\chi \alpha \dfrac {1}{T}$$
  • $$\chi =constant$$

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the center. The substance in the watch glass is (assume poles are far)
  • iron
  • chromium
  • carbon
  • wood
The incorrect statement regarding the lines of force of the magnetic field B is:
  • magnetic intensity is a measure of lines of force passing through unit area held normal to it.
  • magnetic lines of force form a closed curve.
  • inside a magnet, its magnetic lines of force move from the north pole of a magnet towards its south pole.
  • magnetic lines of force never cut each other.
Assertion(A): $$\chi -T$$ graph for a diamagnetic material is a straight line parallel to $$T$$ axis
Reason (R): This is because susceptibility of a diamagnetic material is not affected by temperature
  • both A,R are true and R is the correct explanation of A
  • both A,R are true and R is not correct explanation of A
  • A is true, R is false
  • A is false R is true
When a diamagnetic substance is inserted in a current carrying coil, the magnetic field inside the substance is:
  • decreased
  • increased
  • unchanged
  • increased or decreased depending upon the relative volume of the substance.

The force between two magnetic poles is $$F$$ when they are separated by certain distance. If the distance between the two poles is doubled and strength of each pole is tripled. The percentage change in the force between the two poles is :
  • $$125\%$$
  • $$100\%$$
  • $$50\%$$
  • $$25\%$$
The force of repulsion between two similar magnetic poles each of strength $$2\ Am$$ at a distance $$2\ m$$ from each other in vacuum is :
  • $$10^{-5} N$$
  • $$10^{-7}N$$ 
  • $$10^{-3}N$$ 
  • $$2 \times 10^{-7}N$$ 

For soft iron, in comparison with steel :
  • hysteresis loss is more
  • hysteresis loss is same
  • hysteresis loss is less
  • hysteresis loss is negligible
Two magnetic poles of strengths $$40\ Am$$ and $$10\ Am$$ are separated by a distance of $$20\ cm$$ in air. The force between them if the distance is reduced to $$10\ cm$$ is
  • $$4\times 10^{-3}N, 10^{-3}N$$
  • $$10^{-3}N, 4\times 10^{-3}N$$
  • $$2\times 10^{-3}N, 10^{-3}N$$
  • $$10^{-3}N, 2\times 10^{-3}N$$
Two magnetic poles of equal pole strengths each of $$1.732\ Am$$ should be placed at ___ $$cms$$ apart so that the force of attraction between them is $$0.5\ dynes$$ (nearly) :
  • $$6$$
  • $$2.45$$
  • $$24.5$$
  • $$\sqrt{3}$$

The distance between a north pole of strength $$6\times 10^{-3}Am$$ and south pole of strength $$8\times 10^{-3}Am$$ is $$10\ cm$$. The poles are separated in air. The force between them :
  • $$4.8\times 10^{-11}N$$
  • $$24\times 10^{-11}N$$
  • $$48\times 10^{-11}N$$
  • $$24\times 10^{-12}N$$
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