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प्रश्न
What happens to a ferromagnetic material when its temperature increases above curie temperature?
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उत्तर
A ferromagnetic material is made up of small regions known as domains. The atomic magnetic moments of nearest-neighbour atoms interact strongly within each domain via exchange interaction, a quantum mechanical phenomenon, and align parallel to each other even in the absence of an external magnetic field. As a result, a domain is spontaneously magnetised to saturation.
Only up to a specific temperature does the material keep its domain structure. When heated, the increased thermal agitation opposes spontaneous domain magnetization. Finally, at a critical temperature known as the Curie point or Curie temperature, thermal agitation overcomes the exchange forces and maintains the atomic magnetic moments randomly oriented. As a result, the material becomes paramagnetic above the Curie point. The ferromagnetic to paramagnetic transition is a transition from order to disorder. The material becomes ferromagnetic again when cooled below the Curie point.
संबंधित प्रश्न
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(a) 0.45 mV
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Answer in brief.
Discuss the Curie law for paramagnetic material.
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
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Most of the substance show which of the magnetic property:-
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- Assertion (A): Diamagnetic substances exhibit magnetism.
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Explain the meaning of the following statement:
Curie temperature for soft iron is 770°C.
Match List-I with List-II.
| List-I (Material) | List-II (Susceptibility) | ||
| A. | Diamagnetic | I. | χ = 0 |
| B. | Ferromagnetic | II. | 0 > χ ≥ −1 |
| C. | Paramagnetic | III. | χ >> 1 |
| D. | Non-magnetic | IV. | 0 < χ < ε |
Choose the correct answer from the options given below:
Which substances are feebly magnetised in a direction opposite to that of the magnetising field?
Which substances are feebly magnetised in the direction of the magnetising field?
Which substances are strongly magnetised in the direction of the magnetising field?
What is the susceptibility of diamagnetic substances?
How do ferromagnetic substances respond to a magnetic field?
Which list contains only examples of diamagnetic substances?
Which list contains only examples of paramagnetic substances?
What happens to paramagnetic substances on cooling at the Curie temperature?
What causes the magnetic behaviour of ferromagnetic substances?
How are the tiny domains oriented in an unmagnetised ferromagnetic specimen?
