-: Superconductivity :-
Superconductivity is a phenomenon observed in several materials and ceramic materials . When some materials are cooled to temperature about absolute zero then electrical resistivity of the material suddenly zero then this state of material is known as Superconductivity .
This phenomenon was observed by H. Kamerlingh in 1911 during study of variation of electrical resistivity of the materials with respect to temperature . One day Kamerlingh was observing variation of electrical resistivity of mercury with new scale ( Kelvin ) . On increasing the temperature resistivity of mercury gradually decreases ;. At 4.2 Kelvin resistivity of mercury suddenly become zero i.e. below 4.2 Kelvin mercury behave like superconductor and above 4.2 kelvin behave like normal conductor.
Later 1913 he warn a Noble prize in Physics .
-: Types of Superconductors :-
Superconductors are of following two types -
1- Low temperature superconductor or Soft or Type (I) superconductor
2- High temperature superconductor or hard or Type (II) superconductor
1- Low temperature superconductor :-
A superconductor which exactly follow the Meissner Effect is called soft superconductor .
2- High Temperature superconductor :-
A superconductor which does not exactly follow the Meissner effect is called hard superconductor .
-: Properties of Superconductor :-
or
[Essential Properties of superconductivity i.e. zero resistivity ]
1- Superconductivity occurs in those materials which have high resistivity in normal state .
2- Superconductivity has been normally observed only for those metallic substances for which the number of valence electrons lies between 2 to 8 .
3- Ferromagnetic ( Fe , Ni , Co ) and Anti-ferromagnetic ( FeO , CaO , MnS ) materials are not superconductors .
4- Superconducting materials are not very good conductors at room temperature in the normal state .
5- Bi , Sb , and Tl becomes superconductors under high pressure .
-: Characteristics of Superconductors in Superconducting state :-
On the basis of observed fact , the characteristics of superconductors are classified as-
1- Characteristics that change in superconducting transitions
2- Characteristics which remain unchanged during superconducting transitions
1- Characteristics that change in superconducting transitions:-
(i)- When a material converts into superconductors then external magnetic field does not penetrate into the superconducting material . This property is known as Meissner effect .
(ii)- A superconductor heat of a material abruptly change when it transit from normal to superconducting state .
(iii)- A superconductor has infinite conductivity for D.C. but shows a resistance for certain frequency of A.C.
(iv)- All the thermo-electric effects disappear in the superconducting state .
(v)- In all superconductors , entropy decreases significantly on cooling below the critical temperature .
(vi)- Superconductivity is lower for pure metals , but higher for certain alloys .
2- Characteristics which remain unchanged during superconducting transitions :-
(i)- The appearance of X-Ray diffraction pattern is same in both normal and superconducting states i.e. no change in crystal lattice structure .
(ii)- The change in the electronic structure in superconducting state is negligible .
(iii)- The photoelectric characteristics of a metal do not change in the superconducting transitions from normal state .
(iv)- The reflectivity in the visible and infrared regions remains unchanged during the superconducting transition from normal state to superconducting state .
(v)- The elastic properties in both normal and superconducting states of a metal are same .
-: Application of Superconductor :-
There are following some important application of superconductor is given as -
1- Superconducting Magnets :- Similar to electromagnetic , superconducting magnets can also be formed by using coils of wire made up of super conducting materials . The benefits of using superconducting magnets instead of electromagnets is the cost of power required to maintain superconductors at low temperature will be 1000 times less than the cost of power required in case of electromagnets to produce the same magnetic field . Superconducting magnets are made of type (II) superconducting material .
2- Magnetic Bearing :- Superconducting materials are used to made the magnetic bearing because there is no friction in these bearing .
Meissner Effect is used in these bearing .
3- In Loss Less power transmission :- The D.C. power loss can be eliminated by passing current through a superconductor wire . Foe A.C. , the superconductor show resistance .
4- Superconductor Fuse :- We know that some insulating materials that show superconductivity at low temperature , thin film of such materials can be used instead of fuse because when more than critical current pass through them they change into normal state .
In normal state , they are insulators so that would not conduct current so it will act as a fuse .
5- Computer application :- A closed superconductor ring is used in memory cell , the superconducting memory cell is a binary system .
Also Read -
What is Meissner Effect ?
Superconductivity is a phenomenon observed in several materials and ceramic materials . When some materials are cooled to temperature about absolute zero then electrical resistivity of the material suddenly zero then this state of material is known as Superconductivity .
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This phenomenon was observed by H. Kamerlingh in 1911 during study of variation of electrical resistivity of the materials with respect to temperature . One day Kamerlingh was observing variation of electrical resistivity of mercury with new scale ( Kelvin ) . On increasing the temperature resistivity of mercury gradually decreases ;. At 4.2 Kelvin resistivity of mercury suddenly become zero i.e. below 4.2 Kelvin mercury behave like superconductor and above 4.2 kelvin behave like normal conductor.
Later 1913 he warn a Noble prize in Physics .
-: Types of Superconductors :-
Superconductors are of following two types -
1- Low temperature superconductor or Soft or Type (I) superconductor
2- High temperature superconductor or hard or Type (II) superconductor
1- Low temperature superconductor :-
A superconductor which exactly follow the Meissner Effect is called soft superconductor .
2- High Temperature superconductor :-
A superconductor which does not exactly follow the Meissner effect is called hard superconductor .
-: Properties of Superconductor :-
or
[Essential Properties of superconductivity i.e. zero resistivity ]
1- Superconductivity occurs in those materials which have high resistivity in normal state .
2- Superconductivity has been normally observed only for those metallic substances for which the number of valence electrons lies between 2 to 8 .
3- Ferromagnetic ( Fe , Ni , Co ) and Anti-ferromagnetic ( FeO , CaO , MnS ) materials are not superconductors .
4- Superconducting materials are not very good conductors at room temperature in the normal state .
5- Bi , Sb , and Tl becomes superconductors under high pressure .
-: Characteristics of Superconductors in Superconducting state :-
On the basis of observed fact , the characteristics of superconductors are classified as-
1- Characteristics that change in superconducting transitions
2- Characteristics which remain unchanged during superconducting transitions
1- Characteristics that change in superconducting transitions:-
(i)- When a material converts into superconductors then external magnetic field does not penetrate into the superconducting material . This property is known as Meissner effect .
(ii)- A superconductor heat of a material abruptly change when it transit from normal to superconducting state .
(iii)- A superconductor has infinite conductivity for D.C. but shows a resistance for certain frequency of A.C.
(iv)- All the thermo-electric effects disappear in the superconducting state .
(v)- In all superconductors , entropy decreases significantly on cooling below the critical temperature .
(vi)- Superconductivity is lower for pure metals , but higher for certain alloys .
2- Characteristics which remain unchanged during superconducting transitions :-
(i)- The appearance of X-Ray diffraction pattern is same in both normal and superconducting states i.e. no change in crystal lattice structure .
(ii)- The change in the electronic structure in superconducting state is negligible .
(iii)- The photoelectric characteristics of a metal do not change in the superconducting transitions from normal state .
(iv)- The reflectivity in the visible and infrared regions remains unchanged during the superconducting transition from normal state to superconducting state .
(v)- The elastic properties in both normal and superconducting states of a metal are same .
-: Application of Superconductor :-
There are following some important application of superconductor is given as -
1- Superconducting Magnets :- Similar to electromagnetic , superconducting magnets can also be formed by using coils of wire made up of super conducting materials . The benefits of using superconducting magnets instead of electromagnets is the cost of power required to maintain superconductors at low temperature will be 1000 times less than the cost of power required in case of electromagnets to produce the same magnetic field . Superconducting magnets are made of type (II) superconducting material .
2- Magnetic Bearing :- Superconducting materials are used to made the magnetic bearing because there is no friction in these bearing .
Meissner Effect is used in these bearing .
3- In Loss Less power transmission :- The D.C. power loss can be eliminated by passing current through a superconductor wire . Foe A.C. , the superconductor show resistance .
4- Superconductor Fuse :- We know that some insulating materials that show superconductivity at low temperature , thin film of such materials can be used instead of fuse because when more than critical current pass through them they change into normal state .
In normal state , they are insulators so that would not conduct current so it will act as a fuse .
5- Computer application :- A closed superconductor ring is used in memory cell , the superconducting memory cell is a binary system .
Also Read -
What is Meissner Effect ?
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