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
Define the formula of Wien law. WIEN'S LAW: λ m T = constant Here: λ m = Peak Wavelength (m) T = Surface Temperature (K) Constant = 2.898 x 10 -3 mK It

Explain process of Carnot cycle Carnot cycle having of two adiabatic and two isothermal processes, all are reversible. To explain the carnot cycle, suppose the working substanc

A man pushes a couch a distance of 0.75 m. If 113 J of work is done. what is the magnitude of the horizontal force applied?

At the neutral position, magnetic field because of the bar magnet is just equal and opposite to the horizontal component of earth's magnetic field.

Define Gas in Harmonic Well? A classical system of N distinguishable no interacting particles of mass m is placed in a three-dimensional harmonic well: a) Discover t

why effective mass are tensor quantities

Eddy current loss is proportional to the (A) Frequency.                       (B) Square of the frequency. (C) Cube of the frequency.    (D) Square-root of the frequency.

Basic principles of spectrophotometry: An absorbance spectrophotometer is an instrument that measures the fraction of the incident light transmitted through a solution

Beryllium copper alloy: It is obtained by alloying copper and beryllium. These alloys containing beryllium up to 2.75% can be produced in the form of sheet, rod, wire and tube. Be

A silicon material is subjected to a magnetic field of strength 1000A/m. If the magnetic susceptibility of silicon is -0.3x10-5, calculate its magnetization and magnetic flux densi