Class 12 Magnetism And Matter CBSE Questions & Answers

Class 12 · Magnetism And Matter

This is Physics Class 12 Magnetism and Matter CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
magnetic permeability of the substance \(\mu \) is
  • A
    \({\mu _0}{\mu _{\rm{r}}}\)
    Correct
  • B
    \({\mu _0}^{{\rm{1}}.{\rm{2}}}{\mu _{\rm{r}}}\)
  • C
    \({\mu _0}^{0.{\rm{8}}}{\mu _{\rm{r}}}\)
  • D
    \({\mu _0}^{{\rm{1}}.{\rm{5}}}{\mu _{\rm{r}}}\)
2
Magnetic material differences are explained by
  • A
    number of neutrons
  • B
    number of protons
  • C
    atoms contain moving electrons, and these electrons form microscopic current loops that produce magnetic fields of their own.
    Correct
  • D
    atoms contain spinning electrons, and their spin forms microscopic current loops that produce magnetic fields
3
Diamagnetic substances are
  • A
    those that develop a net magnetic moment in direction of applied field
  • B
    those that are uneffected by external magnetic fields
  • C
    those which have tendency to move from stronger to the weaker part of the external magnetic field
    Correct
  • D
    those which have tendency to move from weaker to the stronger part of the external magnetic field
4
For diamagnetic materials
  • A
    additional field caused by atoms is always perpendicular in direction to that of the external field
  • B
    additional field caused by atoms is always opposite in direction to that of the external field
    Correct
  • C
    additional field caused by atoms is always in same direction as that of the external field
  • D
    additional field caused by atoms is always parallel in direction to that of the external field
5
For paramagnetic materials
  • A
    orbital magnetic moments of the electrons are zero
  • B
    orbital and spin magnetic moments of the electrons are of the order of bohr magneton
    Correct
  • C
    orbital and spin magnetic moments of the electrons are less than zero
  • D
    spin magnetic moments of the electrons are zero
6
In Ferromagnetic materials
  • A
    strong interactions between atomic magnetic moments cause them to line up anti parallel to each other in external field
  • B
    strong interactions between atomic magnetic moments cause them to line up parallel to each other in regions called magnetic domains even if there is no external field
    Correct
  • C
    weak interactions between atomic magnetic moments cause them to line up anti parallel to each other in external field
  • D
    atomic magnetic moments are random in strong external fields
7
permanent magnets should have
  • A
    high retentivity and high coercivity
    Correct
  • B
    low retentivity and high coercivity
  • C
    high retentivity and low coercivity
  • D
    low retentivity and low coercivity
8
For strong electromagnets use is made of
  • A
    ferromagnetic core
    Correct
  • B
    paramagnetic core
  • C
    air core
  • D
    diamagnetic core
9
The angle of dip at a location in southern India is about \({18^0}\) . Dip angle in Britain would be
  • A
    greater
    Correct
  • B
    smaller
  • C
    \({18^0}\)
  • D
    0.0
10
If you made a map of magnetic field lines at Melbourne in Australia, would the or of the ground?
  • A
    lines seem to be horizontal to the ground
  • B
    lines seem to come out at 45 degrees to the ground
  • C
    lines seem to come out of the ground
    Correct
  • D
    lines seem to go into the ground
11
To increase the magnetic field of a solenoid what core material should be used ?
  • A
    Ferromagnetic material
    Correct
  • B
    paramagnetic material
  • C
    Ferrimagnetic material
  • D
    diamagnetic material
12
If the area under the B-H curve of a material M is more, in an ac solenoid using material M
  • A
    heat generated is very low d
  • B
    no heat is generated
  • C
    more heat is generated
    Correct
  • D
    heat generated is ultra low
13
If we wanted to cancel the Earth’s magnetic field by running an enormous current loop around the equator, which way would the current have to flow: or west to east?
  • A
    West to east
    Correct
  • B
    east to west
  • C
    north to south
  • D
    south to north
14
the magnetic needle has magnetic moment \({\rm{6}}.{\rm{7 }} \times {\rm{ 1}}{0^{-{\rm{2}}}}{\rm{A}}{{\rm{m}}^{\rm{2}}}\) and moment of inertia \( = {\rm{ 7}}.{\rm{5 }} \times {\rm{ 1}}{0^{-{\rm{6}}}}{\rm{kg }}{{\rm{m}}^{\rm{2}}}\). It performs 10 complete oscillations in 6.70 s. Magnitude of the magnetic field is
  • A
    0.01 T
    Correct
  • B
    0.005 T
  • C
    0.02 T
  • D
    0.015 T
15
Assuming one unpaired electron spin per atom, saturation magnetization in a long cylinder of iron is(n for iron is \({\rm{8}}.{\rm{6 }} \times {\rm{1}}{0^{{\rm{28}}}}\) atoms/m3,Bohr magneton \( = {\rm{9}}.{\rm{27}} \times {\rm{ 1}}{0^{ - {\rm{24}}}}{\rm{J}}/{\rm{T}})\)
  • A
    \({\rm{9}}.0{\rm{ }} \times {\rm{1}}{0^{\rm{5}}}{\rm{A}}/{\rm{m}}\)
  • B
    \({\rm{7}}.0{\rm{ }} \times {\rm{1}}{0^{\rm{5}}}{\rm{A}}/{\rm{m}}\)
  • C
    \({\rm{6}}.0{\rm{ }} \times {\rm{1}}{0^{\rm{5}}}{\rm{A}}/{\rm{m}}\)
  • D
    \({\rm{8}}.0{\rm{ }} \times {\rm{1}}{0^{\rm{5}}}{\rm{A}}/{\rm{m}}\)
    Correct