Effect of field on superconductivity and meissner effect, Physics

EFFECT OF FIELD ON SUPERCONDUCTIVITY: Critical Magnetic field, Hc is the maximum field that can be applied to a superconductor without destroying the superconducting behaviour. It decreases from its maximum value at absolute zero to zero at the critical temperature Tc. On the other hand, Critical Temperature Tc, ­is a temperature that separates superconducting states from the normal state. Above Tc the substance is the normal state whit a finite resistivity but below Tc it is in super conducting state whit zero resistivity. The transition temperature of a superconductor can be reduced by the application of a magnetic field. Whit reference to suppose a superconductor has a temperature Tc. If magnetic field H is applied, the material remains super conducting until a critical field Hc is reached such that for H >Hc, the material is in the normal state. The transition from the superconducting to the normal state under influence of a magnetic field is reversible. The function Hc (T) follows with good accuracy a formula from here ho is the critical field at 0K, Tc is the critical temperature for a given specimen.

MEISSNER EFFECT: The Meissner effect (or Meissner-Ochsenfeld Effect) is the total exclusion of any magnetic flux from the interior of a superconductor. A superconductor below its critical temperature expels all the magnetic field from the bulk of the sample as if it were a perfectly diamagnetic substance. This phenomenon is known as the Meissner effect. Suppose that we place a super conducting material in a magnetic field above Tc. The magnetic field lines will penetrate the sample. However, when the as depicted in fig. 6.3(a). The super conductor develops a magnetization M by developing surface currents, such that M and the applied field cancel everywhere inside the sample. Thus, below Tc a superconductor is a perfectly diamagnetic substance (χm= -1). Now for the case of a perfect conductor in a magnetic field and then cool it below. The magnetic field is not rejected. These two types of behaviour are identified. If we switch off the field, the field around the super conductor simply disappears. But switching off the field means there is a decreasing applied field. This change in the field induces current in the perfect conductor by virtue of Faraday’s law of induction.  

 

Posted Date: 7/9/2012 2:29:38 AM | Location : United States







Related Discussions:- Effect of field on superconductivity and meissner effect, Assignment Help, Ask Question on Effect of field on superconductivity and meissner effect, Get Answer, Expert's Help, Effect of field on superconductivity and meissner effect Discussions

Write discussion on Effect of field on superconductivity and meissner effect
Your posts are moderated
Related Questions
Determine the Shear Force in kN rounded to 1 DP and Bending Moment in kN.m rounded to 1 DP at point C in the beam when the couple at the left hand end is P49 kN.m and the point loa

Rydberg constant (Rydberg): A constant that governs the relationship of the spectral line features of an atom by the Rydberg formula. For hydrogen, it is about 1.097 x 10 7 m

Hookes Law Hooke's equation actually holds (to some extent) in several other situations whereas an elastic body is deformed, like as wind blowing on a tall building, a musician

In an experiment of Quink tube source freequence 100 Hz is used to find 2nd maxima to 4th manima movalbe part of tube displaced by 1cm then calculate speed of sound in air

A stack emitting 85 g/s of NO has an effective stack height of 100 m. The wind speed is 3 m/s at 10 m, and it is a cloudy summer day.  Estimate ground level NO concentration:

Determine the inductance of a solenoid of 2000 turns round uniformly over a length of 50 cm on a cylindrical paper tube 4 cm in diameter. The medium is air.

what are some advantages of the thermo-electric thermometer over the mercury in glass thermometer?

#how does multihance work in mra and how does it improve mri image quality?question..

ENERGY LEVELS The energy levels, measured in electron volts (e.v.) in which orbiting electrons exist comply with a law of physics which states that energy can be given to elect

Explain the basic concept of sonar. Basic concept of SONAR: Sonar is based ontpo the echo-sounding technique of ultrasound. While an ultrasonic wave is transmitted by water,