CBSE Questions for Class 12 Medical Physics Magnetism And Matter Quiz 15 - MCQExams.com

$$M$$ and $$M\sqrt {3}$$ are the magnetic dipole moments of the two magnets, which are joined to form a cross figure. The inclination of the system with the field, if their combination is suspended freely in a uniform external magnetic field $$B$ is
1325098_9c9dbe97607746cf818c6c4ebfa83bbc.jpg
  • $$\theta = 30^{\circ}$$
  • $$\theta = 45^{\circ}$$
  • $$\theta = 60^{\circ}$$
  • $$\theta = 15^{\circ}$$
A ferromagnetic material is placed in an external magnetic field. The magnetic domains 
  • Increase in size
  • Decrease in size
  • May increase or decrease is size
  • Have no relation with the field
The number of magnetic field lines passing through a unit area placed which is perpendicular to
  • Magnetic field
  • Magnetic flux
  • Magnetic force
  • Magnetic moment
Choose the correct examples for the ferro magnetic material.
  • Aluminum
  • Copper
  • Steel
  • Cobalt
A bar magnet freely suspended in a vibration magnetometer has time period T at a place A and T/2 at a place B. If horizontal component of earth's magnetic field at A is $$36 \times 10^{-6}$$  T, then its value at 'B' is
  • $$100 \times 10^{-6}$$
  • $$72 \times 10^{-6}$$
  • $$144 \times 10^{-6}$$
  • None
Two magnets have their length in the ratio $$2:3$$ and their pole strengths in the ratio $$3:4$$. The ratio of their magnetic moment is
  • $$2:1$$
  • $$4:1$$
  • $$1:2$$
  • $$1:4$$

The mass of a specimen of a ferromagnetic material is 0.6 kg and the density is $$7.8 \times {10^3}\;{\text{kg}}\;{{\text{m}}^{{\text{ - 3}}}}$$ . If the area of the hysteresis loop of the alternating magnetizing field of frequency 50 Hz is 0.722 MKS units, then hysteresis loss per second will be 
  • $$27.77 \times {10^{ - 5}}{\text{J}}$$
  • $$2.777 \times {10^{ - 5}}{\text{J}}$$
  • $$27.77 \times {10^{ - 4}}{\text{J}}$$
  • $$27.77 \times {10^{ - 6}}{\text{J}}$$
A wheel having metal spokes of 1 m long between its axis and rim is rotating in a magnetic field of flux density $$5\times { 10 }^{ -5 }T$$ normal to the plane of the wheel. An emf of $$(\dfrac { 22 }{ 7 } )$$ mV is produced between the rim and the axle of the wheel. The rate of rotation of the wheel in radian per second is 
  • 10 rotation/sec
  • 20 rotation/sec
  • 30 rotation/sec
  • 40 rotation/sec
At a certain location in Africa, a compass points $${ 12 }^{ \circ  }$$ West of the geographic North. The North tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points $${ 60 }^{ \circ  }$$ above the horizontal. The horizontal component of the earth's field is measured to be $$0.16 G$$. The magnitude of the earth's field at the location will be:-
  • $$0.23\times10^{-4} T$$
  • $$0.18\times10^{-4} T$$
  • $$0.32\times10^{-4} T$$
  • $$0.81\times10^{-4} T$$
If a diamagnetic material is placed in a magnetic field,the flux density inside the material compared to that outside will be:
  • Slightly less
  • Slightly more
  • Very much more
  • Same

What is the type of field line of a magnetic field passing through the centre of current carrying circular ring?
  • Circular
  • Straight lines
  • Ellipse
  • Magnetic field is zero at centre
If the distance between two isolated magnetic poles be increase by 3% then approximate percentage change in the force between them will be 
  • increase by 9%
  • decrease by 9%
  • decrease by 6%
  • increase by 8%
A current carrying closed loop in the form of a right angle isosceles triangle $$ABC$$ is placed in a uniform magnetic field acting along $$AB$$. If the magnetic force on the arm $$BC$$ is $$\overrightarrow { F } $$, the force on the arm $$AC$$ is
1499154_c15168d8445b4a57accb8886619b82ec.png
  • $$\sqrt{2} \overrightarrow { F } $$
  • $$-\sqrt{2} \overrightarrow { F } $$
  • $$ -\overrightarrow { F } $$
  • $$ \overrightarrow { F } $$
Alkali metals dissolve in liquid $$  \mathrm{NH}_{3}  $$ forms blue colour solution which is paramagnetic, conductive. What happen to the magnetic property and conductivity by increasing concentration of alkali metal in liquid ammonia when color changes from blue to bronze?
  • Paramagnetic character increases
  • Conductivity decreases
  • Paramagnetic character decreases
  • Conductivity increases
A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a curent of 5.2 A. The coercivity of the bar magnet is:
  • 2600 A/m
  • 520 A/m
  • 285 A/m
  • 1200 A/m
A para magnetic material has $${ 10 }^{ 28 }atoms/{ m }^{ 3 }$$. Its magnetic susceptibility at temperatures 350 K is $$2.8\times { 10 }^{ -4 }$$. Its susceptibility at 300 K is:  
  • $$3.672\times { 10 }^{ -4 }$$
  • $$3.267\times { 10 }^{ -4 }$$
  • $$3.726\times { 10 }^{ -4 }$$
  • $$2.672\times { 10 }^{ -4 }$$
Magnetic field lines are __________.
  • open curves
  • closed curves
  • Both A & B
  • None of the above
Magnetic field lines cross each other.
  • True
  • False
The field lines emerge from _______ and merge at ________.
  • east pole, west pole
  • south pole, north pole
  • west pole, east pole
  • north pole, south pole
An iron is placed parallel to magnetic field of intensity $$ 2000 Am^{-1} $$ .The magnetic  flux through the rod is $$ 6 \times 10^{-4} $$ Wb and its cross  -  sectional area is $$ 3 cm^{2} $$. The magnetic permeability of the rod in Wb $$ A^{-1} m ^{-1} /s $$
  • $$ 10^{-1} $$
  • $$ 10^{-2} $$
  • $$ 10^{-3} $$
  • $$ 10^{-4} $$
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