PHY_10_51_V2_P_Supercond
Оценка 5

# PHY_10_51_V2_P_Supercond

Оценка 5
ppt
07.05.2020
PHY_10_51_V2_P_Supercond.ppt

## Superconductivity LO: 10.3.3

Superconductivity

LO:
10.3.3.4 - describe the phenomenon of superconductivity and its practical application;

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## What is electric current? What are the conditions for the existence of an electric current?

What is electric current?
What are the conditions for the existence of an electric current?
What is resistance?
What is the great disadvantage of transmitting power through copper wires?
How the temperature changes with the increasing of temperature?
How the temperature changes with the decreasing of temperature?

REVISION QUESTIONS:

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## SUPERCONDUCTIVITY Questions :

SUPERCONDUCTIVITY
Questions:
What is a superconductivity?
How do we know the resistance of a superconductor is zero?
What is a Critical Temperature
Who discovered thes phenomena?

Applications of superconducting metals
Questions:
What is a superconducting magnet?
Applications of a superconducting magnet?
What is a Superconducting power cables
Applications of a Superconducting power cables

A MAGLEV TRAIN.
Questions:
What is a maglev train?
How does it works?

Group work activity:

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Superconductivity was first discovered in 1911 by the

Superconductivity was first discovered in 1911 by the Dutch physicist, Heike Kammerlingh Onnes.

Superconductivity is the flow of electric current without resistance in certain metals, alloys, and ceramics at temperatures near absolute zero, and in some cases at temperatures hundreds of degrees above absolute zero = -273ºK.

Superconductivity

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Discovery Onnes, felt that a cold wire's resistance would dissipate

The Discovery

Onnes, felt that a cold wire's resistance would dissipate. This suggested that there would be a steady decrease in electrical resistance, allowing for better conduction of electricity.
At some very low temperature point, scientists felt that there would be a leveling off as the resistance reached some ill-defined minimum value allowing the current to flow with little or no resistance.

Onnes passed a current through a very pure mercury wire and measured its resistance as he steadily lowered the temperature.
Much to his surprise there was no resistance at 4.2K.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Science of Superconductivity

The Science of Superconductivity

Superconductors have the ability to conduct electricity without the loss of energy. When current flows in an ordinary conductor, for example copper wire, some energy is lost.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Science of Superconductivity, cont

The Science of Superconductivity, cont.

The behavior of electrons inside a superconductor is vastly different.
The impurities and lattice framework are still there, but the movement of the superconducting electrons through the obstacle course is quite different.
As the superconducting electrons travel through the conductor they pass unobstructed through the complex lattice.
Because they bump into nothing and create no friction they can transmit electricity with no appreciable loss in the current and no loss of energy.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Science…. An electrical current in a wire creates a magnetic field around the wire

The Science….

An electrical current in a wire creates a magnetic field around the wire.
The strength of the magnetic field increases as the current in the wire increases.
Because superconductors are able to carry large currents without loss of energy, they are well suited for making strong electromagnets.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Applications Soon after Kamerlingh

Applications

Soon after Kamerlingh Onnes discovered superconductivity, scientists began dreaming up practical applications for this strange new phenomenon.
Powerful new superconducting magnets could be made much smaller than a resistive magnet, because the windings could carry large currents with no energy loss.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Application Generators wound with superconductors could generate the same amount of electricity with smaller equipment and less energy

Application

Generators wound with superconductors could generate the same amount of electricity with smaller equipment and less energy. Once the electricity was generated, it could be distributed through superconducting wires.
Energy could be stored in superconducting coils for long periods of time without significant loss.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Science…. The superconducting state is defined by three very important factors: critical temperature (

The Science….

The superconducting state is defined by three very important factors: critical temperature (Tc), critical field (Hc), and critical current density (Jc). Each of these parameters is very dependant on the other two properties present
critical temperature (T ) The highest temperature at which superconductivity occurs in a material. Below this transition temperature T the resistivity of the material is equal to zero.
critical magnetic field (Hc ) Above this value of an externally applied magnetic field a superconductor becomes nonsuperconducting
critical current density (Jc) The maximum value of electrical current per unit of cross-sectional area that a superconductor can carry without resistance.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## The Meissner Effect Levitation of a magnet above a cooled superconductor, the

The Meissner Effect

Levitation of a magnet above a cooled superconductor, the Meissner Effect,
If a superconductor is cooled below its critical temperature while in a magnetic field, the magnetic field surrounds but does not penetrate the superconductor. The magnet induces current in the superconductor which creates a counter-magnetic force that causes the two materials to repel.
This can be seen as the magnet is levitated above the superconductor.

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Demonstration of the Meissner Effect https://www

Demonstration of the Meissner Effect

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Current Applications of Superconductors magnetic shielding devices medical imaging systems, e

Current Applications of Superconductors

magnetic shielding devices
medical imaging systems, e.g. MRI’s
superconducting quantum interference devices (SQUIDS) used to detect extremely small changes in magnetic fields, electric currents, and voltages.
infrared sensors
analog signal processing devices
microwave devices

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Emerging Applications power transmission superconducting magnets in generators energy storage devices particle accelerators levitated vehicle transportation rotating machinery magnetic separators

Emerging Applications

power transmission
superconducting magnets in generators
energy storage devices
particle accelerators
levitated vehicle transportation
rotating machinery
magnetic separators

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

## Cable – transmits 3 to 5 times more energy than copper wire

Cable – transmits 3 to 5 times more energy than copper wire

Source: Southwire

PHY_10_51_V2_P_ SUPERCONDUCTIVITY AND ITS APPLICATION

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