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Topic Superconductors and their real life applications as a theory of

knowledge

Type Essay

Level Undergraduate 1-2

Style MLA

Sources 5

Description Define superconductors; discuss their properties; describe how they

can be utilized to solve various real life problems

Spacing 2

Pages 6

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Course

Instructor

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Superconductors

Introduction

Superconductors are materials that conduct electricity at adequately low temperatures.

When the temperatures of a superconductor gradually reduce, the resistance also drops slowly

just like in an ordinary conductor. However, the resistance of a superconductor suddenly drops to

zero at a temperature commonly known as the transition temperature or critical temperature (K0/

Tc). For any temperature below the critical temperature, the resistance of the superconductor

remains zero. The critical temperature (Tc) of novel superconductors varies widely from absolute

zero to over 100K for some recently developed compounds of copper-oxide. The graph below

shows the behavior of a superconductor (Rex 35).

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Figure 1: Properties of Superconductors

Superconductors are in two groups according to their properties. They are type I and type

II semiconductors. All the superconductors except Niobium form the type I category. Niobium

and its alloys and chemical compounds form type II, which also consist of the high-Tc

superconductors. One major factor that differentiates the two is their response to the magnetic

effect. Type-I superconductors also exhibit the Meissner effect (Schmidt 6-7).

Type-I semiconductors

During the magnetization of a type-I superconductor, the applied magnetic field (external

magnetic field Ho) causes no change to the induction inside the material (B=0). However, as the

value of Ho reaches the value Hcm, the superconductivity of the material gets destroyed. The

applied magnetic field penetrates the material, and the values of B and Ho becomes equal. The

magnetic induction B and magnetic field Ho acquire a relation governed by the equation

(Annett 57-59). The term represented by M stands for the magnetic moment

per unit volume.

The field lines outside any superconductor are tangential to its surface. The lines of

induction B1 becomes closed and continuous. The property of the material satisfies the property

that . The second property of the magnetic material is that when the superconductor

gets in an external magnetic field, a current flows near its surface. When Maxwell's Equations

find use on the above condition, one observes an unusual situation. Only the surface current

occurs, making the internal flow be zero. It is vital to note that the surface current only exists

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when the superconducting material finds a way to the inside of an external magnetic field. In a

case where the external field does not exist, the material would create an own field in the

superconductor. The latter condition is impossible.

Meissner effect is also present in the type I semiconductors. When a magnetic field gets

applied to this kind of superconductor, it expels the magnetic field, making the area of the

material zero. Compared to an average or real metal, when an external magnetic field impacts on

type I, the internal field becomes a constant. The above property shows that the superconductors

are unique. The Meissner effect is demonstrated by cooling a high Tc superconductor and placing

the permanent magnet on top of the superconductor. The permanent magnet gets repelled and

levitated (Wesche 89).

Physicists have tried to explain the levitation of the magnet. According to Poole, Horacio,

and Creswick, the magnet perceives its mirror image in the superconductor as a magnet floating

on the top of an identical magnet (10). It results in a distorted picture of the magnet at the edges

of the superconductor. The whole situation balances the two magnets that would be impossible in

the absence of physical force holding the two magnets apart. Therefore, the observation of the

superconductor on a magnet leaves puzzle worth seeking an answer. In the setup, when one

magnet gets nudged, it springs back to its original position. However, the demonstration of the

experiment has never been right. Most of those researchers who carry out the levitation

experiment tend to hold the magnet over the superconductor rather than letting it go. They only

do it to levitate the magnet stable. However, if the magnet gets released at this point, it remains

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stable. Removing the magnet and then releasing it back over the superconductor levitates it

stably without the need to thrust it in the direction of the superconductor.

Type II semiconductors

The superconductors of type II varies from type I. They do not show the Meissner effect.

When subjected to magnet field, it penetrates the materials in an extraordinary manner. Under the

influence of an external magnetic field, the content rejects and pushes the field out because

magnetic induction in the interior of the material is zero. However, when the area increases to an

absolute value, there is an observation of a finite value of induction. The field at which induction

get first recorded is called the lower particular area (HCl). When the magnetic field increases

further, the general field in the material equals to the external field Ho and the material goes back

to the normal state. The value of the area at which the material goes back to normal is called the

upper critical field (Hcu). When the field exceeds the upper critical field superconductivity, it

remains at the top as a thin surface of the material. When the value of the external field equals to

Ho=1.69Hcu, the superconductivity in the surface layer get destroyed (Ginsberg 183).

Application of semiconductors

After the discovery of the superconductors by Kamerlingh Onnes, other scientists began

to learn many practical applications for the new strange phenomenon. Using the superconductors

facilitated large currents with no energy loss; hence, created powerful superconducting magnets.

Large resistive magnets got replaced by smaller superconducting magnets. Generators with

superconductor windings generated power with less equipment and little energy. Other promising

applications of superconductors are in electrical transmission. Superconductors conduct

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electricity with zero resistance; hence, no loss of power. With the current transmission lines,

there is a substantial loss of electrical energy through heat generation and the charging duration

of the capacitors due to the resistance of the joining metal films. Electrical transmission line

using superconducting cables transport electric power with little power loss over long distances.

However, this phenomenon is possible if a cooling mechanism gets devised.

In the field of electronics, superconductors are very promising. The reduction of the sizes

and increased speed of computer chips find limitations in the excessive generation of heat and

charging time of capacitors. When using superconductors, the result may be more densely

packed chips with high speeds of transmitting information. In the field of digital electronics,

logic gates with delays of 13 picoseconds and switching time of 9 picoseconds have gone

through successful practical demonstration. Other gadgets such as microwave detectors,

SQUIDS, magnetometers and stable voltage sources are made more sensitive by the application

of the Josephson junctions.

In the transportation sector, the superconductors find use in the construction of levitated

trains. In Japan, successful prototypes of the trains were constructed using Helium as a

refrigerant. In the health sector, the Magnetic Resonance Imaging (MRI) plays a crucial role in

diagnostic medicine. Superconductors find use in the powerful magnetic fields required for the

MRI. A closer observation of the current trend of the development of the superconductors reveals

that their new applications increase with a rise in critical temperatures. If superconductors with

critical temperatures equal to room temperatures, then more superconducting devices will come

into existence. Other devices that use superconductors include:

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Superconductor transformers

Superconductors make the transformer windings, thus reducing power losses. The sizes

of the transformers get small, and they become portable. A transformer of 2000 to 3000mW gets

manufactured with a reduced size.

Electric motors and generators

In the production of electrical machines, motors and generators, high efficiency and light

weight are possible if superconductors can be utilized. The use of adamant magnetic fields and

coils with no electric losses is a fascinating phenomenon to the area of power engineering.

However, even the existing superconductors experience losses when used with low frequency

alternating current. The problem gets the solution when newly discovered materials get used.

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Superconducting breakers and fuse

Thin-film superconductors find use in preparation of circuit breakers and switches. After

a current of more than critical density has passed through a thin-insulated superconductor film,

they have the capability to go back to the normal state. Using such films is more efficient than

the regular electric fuses. It is possible to regulate the intensity of current by appropriately

choosing the material for the film. When using the films as a circuit breaker, one should select a

long film. The moment of transition must be at the normal state and the resistance made high

(Ginsberg 39).

Magnetic Mirror and Superconducting Bearing

The zero magnetic induction, responsible for magnetic levitation finds application as

frictionless bearings. In an individual levitation experiment, a horizontal bar magnet got

suspended from a flexible chain and lowered over a sheet of lead cooled to the superconducting

state. As the magnet approached the superconducting sheet, the supporting chain became floppy

and formed a loop below the magnet. It remained in the suspended state above the sheet. In this

regard, the magnetic field of the magnet approaching induced a current in the superconductor's

surface. Since there were zero resistance, the persisting current, and its field repelled the bar

magnet’s current (Poole, Horacio and Creswick 130). Therefore, the superconducting sheet acts

as a mirror that reflects the attraction; hence forming its image.

With proper design, a two-dimensional shaft bearing and three-dimensional support of a

floating sphere get constructed. Other arrangements of superconductors get applications in

superconducting gyroscope having spherical rotor than spins for months without stopping. The

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phenomenon demonstrates an almost frictionless condition. Thus, superconductors as an area of

knowledge is essential in our day to day operations as discussed above, especially in the field of

science. In this regard, more input is required to maximize the real life output that can potentially

be drawn from this area for the benefit of all.

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Work Cited

Annett, F. James. Superconductivity, Superfluids, and Condensates. Oxford: OUP Oxford, 2004.

Print.

Ginsberg, M. Donald. Physical Properties of High-Temperature Superconductors. Singapore:

World Scientific, 1996. Print.

Poole, P. Charles, et al. Superconductivity. Taramani: Elsevier, 2014. Print.

Rex, Andrew. Commonly Asked Questions in Physics. Boca Raton: CRC Press, 2014. Print.

Schmidt. The Physics of Superconductors: Introduction to Fundamentals and Applications.

Berlin: Springer Science & Business Media. , 2013. Print.

Wesche, Rainer. Physical Properties of High-Temperature Superconductors. New Jersey: John

Wiley & Sons, 2015. Print.