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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

The earth’s field departs from its dipole shape substantially at large distances (greater than about 30,000 km). What agencies may be responsible for this distortion?

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प्रश्न

The earth’s field departs from its dipole shape substantially at large distances (greater than about 30,000 km). What agencies may be responsible for this distortion?

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उत्तर

Earth’s field departs from its dipole shape substantially at large distances (greater than about 30,000 km) because of the presence of the ionosphere. In this region, the earth’s field gets modified because of the field of single ions. While in motion, these ions produce the magnetic field associated with them.

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पाठ 5: Magnetism and Matter - Exercise [पृष्ठ २००]

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एनसीईआरटी Physics Part I and II [English] Class 12
पाठ 5 Magnetism and Matter
Exercise | Q 5.2 (e) | पृष्ठ २००

संबंधित प्रश्‍न

The susceptibility of magnesium at 200 K is 1.8 x 10-5. At what temperature will the susceptibility decrease by 6 x 10-6?


Out of the two magnetic materials, 'A' has relative permeability slightly greater than unity while 'B' has less than unity. Identify the nature of the materials 'A' and 'B'. Will their susceptibilities be positive or negative?


Identify the following magnetic materials :

(i) A material having susceptibility (χm) = −0⋅00015.
(ii) A material having susceptibility (χm) = 10−5

Choose the correct option:

A rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely. Its period of oscillation is T′, the ratio of T′/T is ______.


A paramagnetic gas has 2.0 × 1026 atoms/m with atomic magnetic dipole moment of 1.5 × 10−23 A m2 each. The gas is at 27°C.

  1. Find the maximum magnetization intensity of this sample.
  2. If the gas in this problem is kept in a uniform magnetic field of 3 T, is it possible to achieve saturation magnetization? Why?

A rod of magnetic material of cross-section 0.25 cm2 is placed in a magnetizing field of intensity 4000 A/m-1. The magnetic flux passing through the rod is 25 × 10-6 Wb. Find out

(a) relative permeability

(b) magnetic susceptibility and 

(c) magnetisation of the rod.


Two identical bar magnets each of magnetic moment M, separated by some distance are kept perpendicular to each other. The magnetic induction at a point at the same distance d from the centre of magnets, is (µ0 = permeability of free space)


A domain in a ferromagnetic substance is in the form of a cube of side 1 µm. If it contains 8 × 1010 atoms and each atomic dipole has a dipole moment of 9 × 10-24 Am2 then the magnetisation of the domain is ______.


All atoms of a magnetic substance have a resultant magnetic moment even in absence of external magnetic field. The substance is ______.


A short bar magnet has a magnetic moment of 0.48 J T−1. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on

  1. the axis,
  2. the equatorial lines (normal bisector) of the magnet.

Why does a paramagnetic sample display greater magnetisation (for the same magnetising field) when cooled?


The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 × 103 Am–1. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is ______.


According to the Atomic theory, on heating a magnet, the thermal energy of the elementary magnet ______


S is the surface of a lump of magnetic material.

  1. Lines of B are necessarily continuous across S.
  2. Some lines of B must be discontinuous across S.
  3. Lines of H are necessarily continuous across S.
  4. Lines of H cannot all be continuous across S.

  • Assertion (A): Diamagnetic substances exhibit magnetism.
  • Reason (R): Diamagnetic materials do not have a permanent magnetic dipole moment.

Explain the Domain theory in brief.


What is the susceptibility of diamagnetic substances?


What happens to ferromagnetic substances on heating beyond the Curie temperature?


In the small-arrows analogy for ferromagnets, when does the total effect become strong?


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