Advertisements
Advertisements
प्रश्न
Answer in brief.
Discuss the Curie law for paramagnetic material.
Advertisements
उत्तर
Curie's law: The magnetization of a paramagnetic material is directly proportional to the external magnetic field and inversely proportional to the absolute temperature of the material.
If a paramagnetic material at an absolute temperature T is placed in an external magnetic field of induction `vec "B"_"ext"`, the magnitude of its magnetization
`"M"_"z" prop "B"_"ext"/"T"`
∴ `"M"_"z" = "C" "B"_"ext"/"T"`
where the proportionality constant C is called the Curie constant.
संबंधित प्रश्न
Give any ‘two’ points of differences between diamagnetic and ferromagnetic substances.
An iron rod of the area of cross-section 0.1m2 is subjected to a magnetizing field of 1000 A/m. Calculate the magnetic permeability of the iron rod. [Magnetic susceptibility of iron = 59.9, magnetic permeability of vacuum = 4π x 10-7 S. I. unit]
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?
Distinguish between diamagnetic and paramagnetic substances.
The susceptibility of a magnetic material is 0·9853. Identify the type of magnetic material. Draw the modification of the field pattern on keeping a piece of this material in a uniform magnetic field.
Which of the following substances are diamagnetic?
Bi, Al, Na, Cu, Ca and Ni
Which of the following substances are para-magnetic?
Bi, Al, Cu, Ca, Pb, Ni
A tangent galvanometer shows a deflection of 45° when 10 mA of current is passed through it. If the horizontal component of the earth's magnetic field is `B_H = 3.6 xx 10^-5 "T"` and radius of the coil is 10 cm, find the number of turns in the coil.
Identify the following magnetic materials :
Choose the correct option:
A magnetising field of 360 Am−1 produces a magnetic flux density (B) = 0.6T in a ferromagnetic material. What is its permeability in Tm A−1?
What happens to a ferromagnetic material when its temperature increases above curie temperature?
The susceptibility of a paramagnetic material is χ at 27° C. At what temperature its susceptibility be χ/3?
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 ______.
Magnetic material can be easily magnetized if magnetic susceptibility is ______.
The magnetic property of magnetic substance is associated with ____________.
Above the curie temperature the susceptibility of ferromagnetic substance varies ____________.
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?
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
- the axis,
- the equatorial lines (normal bisector) of the magnet.
Which graph shows the variation of magnetic susceptibility (`chi`) with magnetizing field (H) for a paramagnetic substance?
Why does a paramagnetic sample display greater magnetisation (for the same magnetising field) when cooled?
If a toroid uses bismuth for its core, will the field in the core be (slightly) greater or (slightly) less than when the core is empty?
Is the permeability of a ferromagnetic material independent of the magnetic field? If not, is it more for lower or higher fields?
Magnetic field lines are always nearly normal to the surface of a ferromagnet at every point. (This fact is analogous to the static electric field lines being normal to the surface of a conductor at every point.) Why?
Explain qualitatively on the basis of domain picture the irreversibility in the magnetisation curve of a ferromagnet.
What kind of ferromagnetic material is used for coating magnetic tapes in a cassette player, or for building ‘memory stores’ in a modern computer?
A certain region of space is to be shielded from magnetic fields. Suggest a method.
A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?
Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond curie temperature, then it will show ______.
The given figure represents a material which is ______.
Which of the following property shows the property of ferromagnetic substances?
The magnetic susceptibility for diamagnetic materials is ______.
When a ferromagnetic material is created above its curie temperature
Earth's magnetic field analyses has a horizontal component except at:-
For a diamagnetic material
According to the Atomic theory, on heating a magnet, the thermal energy of the elementary magnet ______
A paramagnetic sample shows a net magnetisation of 8 Am–1 when placed in an external magnetic field of 0.6 T at a temperature of 4 K. When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16 K, the magnetisation will be ______.
S is the surface of a lump of magnetic material.
- Lines of B are necessarily continuous across S.
- Some lines of B must be discontinuous across S.
- Lines of H are necessarily continuous across S.
- Lines of H cannot all be continuous across S.
A long solenoid has 1000 turns per metre and carries a current of 1 A. It has a soft iron core of µr = 1000. The core is heated beyond the Curie temperature, Tc.
- The H field in the solenoid is (nearly) unchanged but the B field decreases drastically.
- The H and B fields in the solenoid are nearly unchanged.
- The magnetisation in the core reverses direction.
- The magnetisation in the core diminishes by a factor of about 108.
Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to ______.
- electrostatic field lines can end on charges and conductors have free charges.
- lines of B can also end but conductors cannot end them.
- lines of B cannot end on any material and perfect shielding is not possible.
- shells of high permeability materials can be used to divert lines of B from the interior region.
From molecular view point, discuss the temperature dependence of susceptibility for diamagnetism, paramagnetism and ferromagnetism.
If the magnetizing field on a ferromagnetic material is increased, its permeability ______.
An ammeter of resistance R gives a full-scale deflection when a current of 2 A passes through it. If it is measured with a maximum current of 10 A, the required shunt is ______.
Which of the following cannot modify an external magnetic field as shown in the figure?
Explain the origin of paramagnetism on the basis of atomic structure.
State the dimensions of magnetization.
Explain the meaning of the following statement:
Curie temperature for soft iron is 770°C.
