Superconductor Definition and 151 Threads

If someone(s) would be so kind, I have some complicated curiosities about spinning superconductors. This is not homework. What types of materials can a spinning superconductor lift? Does it only work against gravity, or can it work in any direction? Does it have to be cooled? How much...

Hello. Recently I have been inspired by the classic "drop a NdFeB magnet down a copper tube" demonstration, and I have been thinking about a superconductor falling in an ambient magnetic field. I want to determine the terminal velocity, if one exists. Now, I'm interested only in the effect...

Okay, I know in standard inductors the coil itself causes electrical resistance when AC current is passed through it, but I was wondering if a superconductive coil below its Tc has the same effect? Is there any impedance because the meisser effect does not allow outside magnetic fields to...

can x-rays go through a superconductor when it cooled down to its superconducting state.

Hello: I have been reading up on superconductors and everywhere it mentions that once a current is set up in a superconductor, it persists. I understand this, but no where can I find any information on how in practice a current could initially be "started" in a super conductor and made to...

How the currernt in a superconductor is limited?

EM response function of the "Phase Action" of a BCS superconductor Hello, I am looking for a paper in which people calculated the EM response of phase action of A BCS SC. In the book "Condensed Matter Field Theory" by Altland and Simons, on page 393 they mention such a thing in the discussion...

If you took an insulated fully charged superconducting capacitor, and suddenly warmed it above the critical temperature, what would you observe happen? For example, if the superconductor discharged in space. What form would the energy released take?

Homework Statement Consider a magnet floating over a large piece of superconductor. Treat the magnet as a perfect dipole m floating a distance h from the surface of the superconductor, which we take to be the x–y plane. The dipole is oriented at an angle of θ to the z-axis, and without loss...

Hello my university is giving out little "mini" grants for undergrad research and I was wanting to get involved because it sounds fun/looks good on a resume. The winners would get $500 to spend on a research project of their choosing. All I have to do to enter is fill out some paperwork stating...

Homework Statement Consider a type I superconducting material with a parabolic coexistence curve separating the uniform superconducting and normal phases. H is the external magnetic field and T is temperature. Ignore the tiny magnetization of the normal phase. The critical field is Hc = H0...

I'm curious, neglecting all the worries about temperature, etc (assume those conditions can be met)... Is there a limit to the amount of energy that can be stored in a superconductor? Is there a formula to calculate it? What causes this limit, etc? Is there a massive field generated by the...

Hi Please explain Flux Motion Resistance in Superconductors which causes a superconductor to lose energy after a finite period of time. (Theoretically it shouldn't)

hi, A teacher at school was demonstrating some of the properties of superconductors and that got me thinking if it would be possible to get a person to hover. I did a bit of research and it seems that not only is this possible but it's already been done. I saw some videos of small toy...

Problem Statement In a recent exam, I was asked the following question: "A superconducting disc is suspended on strings (horizontally, flat side facing ground) and cooled below it's critical temperature. A bar magnet is placed on a spinning axle under the disc. What happens to the disc once the...

Here's the question: How can we describe a sudden change in the cross sectional area of a super conductor carying a current i from bigger A1 to smaller A2, such that the current density J after change is higher than Jc ? I have one scenario in my mind, the tempreture rises in the...

Hello all, I'm in the process of designing my own electromagnets, and would like to know the benefits(if any) of using superconducting wire at 77K( liquid nitrogen cooled) rather than an equivalent length of copper wire cooled to those temperatures in creating a solenoid. Because the critical...

it has always mystified me how a supercurrent can flow forever in a superconductor. seems like perpetual motion to me. it ocurrs to me now that the simplest explanation is that there is no actual current at all. that nothing is actually flowing in any supercurrent. that the supercurrent merely...

I have this problem here that I don't understand: The critical temperature of a superconductor, TC varies with the isotopic mass of the element making up the superconductor, M, according to the relation TC *square root(M) = a constant. In lead, TC = 7.184 K for the isotopic molar mass 207.7 g...

As described here: http://www3.interscience.wiley.com/journal/112748702/abstract All superconductors are solids in their superconducting state, this state of matter presently having only been observed well below the melting temperature of the solid. The discovery of high-temperature...

Hi I just wanted to know if a charge passing through a superconductor will diminish its current. I know superconductors will keep a current as long as they are kept cool, and I know that a moving charge will produce a magnetic field. However, will this produced magnetic field reduce the...

I need to buy a superconductor for a simple project. I'm only demonstrating how it floats on a magnetic track. Where could I find a superconductor that will work under Liquid Nitrogen's temperature, and is around 2-5 inches in diameter? I've only been able to find very tiny (about...

I was wondering also if you put a magnet above it, then lifted the magnet up,would the nitrogen and salt come up too?

I have a science fair coming up for school, and while I have been doing a ton of research, I have a few questions. I am attempting to recreate an experiment in which a supercondcutor levitates back and forth along a track of permanent magnets. The track consists of 23 magnets, 3 magnets to a...

A new superconductor has been developed at Brookhaven National Laboratory: http://news.yahoo.com/s/nm/20081008/sc_nm/us_superconductor_2 The superconductor is at the junction between two non-superconducting materials, is about 1 nm thick, and has a transition temperature of 50K.

Problem Statement: when a superconductor of the first order is under the influence of an external magnetic field, the field is repelled from the the supercondutin material until the field reaches a critical value called the critical field H_c(T). for H>H_c the material turns into regualr metal...

Could you please spot where is the fault in this reasoning? I suspect that some of the relations may not be applicable and needs to be substituted with something else (or I'm just making a gross mistake as usual...): Speed of light in a material: c=\sqrt{\frac{1}{\epsilon\mu}} where...

For a super conductor there is a maximum current after which the energy of electrons will be higher than Fermi energy and no cooper pairs will exist . Can this be evaded if we used linear superconductors rather than coils ?? thus, the motion of electron pairs could be inertial , And the...

What is the difference, apart from the Meissner effect? What are the practical consequences of Meissner effect? How can I, by experiment, deduce whether a material is an ideal conductor or superconductor? superconductor has zero resistivity. So what happens when we apply a potential...

Hello everyone! My brother is having a science fair coming up. He is doing it over superconductors. We have the Meissner effect down just fine, but I have this idea to pass a current through the ceramic in its superconducting state. We want to show the difference in brightness of a little...

I have to complete a project in a weeks time but i am missing a vital part to the project. I am building a model of a levitating train and have all the magnets and tracks ready i also have liquid nitrogen ordered, unfortunately i am unable to find any form of superconductor. Any help is...

Hi From what I understand the Meissner effect occurs when a current is induced in a superconductor, from a magnet, giving rise to a magnetic field from the superconductor that opposes the magnet. What stops the magnet from being completely repelled away from the superconductor when it is...

Homework Statement Consider a sphere of type 1 superconductor with critical field Hc. (a) Show that in the Meissner regime the effective magnetisation M ithin the sphere is given by -3B_a/2\mu_0 (where Ba is the uniform applied magnetic field). (b) Show that the magnetic field at the surface...

Cool a cylinder made from a Type I superconducting material below the superconducting transition temperature. Apply a magnetic field parallel to the cylinder. The cylinder expels the flux.. up until the field reaches a critical value. Why does a critical value exist? That is, why doesn't...

Hi, does anyone know how superconductors will oppose a magnetic flux even if it is unchanging. Thanks

If you missed the paper in this week's Nature, let's just say that this is an unexpected discovery. You can read a report of it in PhysicsWeb http://physicsweb.org/articles/news/10/11/19/1 Zz.

"ceramic" can become a superconductor State why some insulatores such "ceramic " can become a superconductor when cooled to a temprature of 0 K. :confused:

As I understand it, flux pinning is when a material becomes a superconductor in the presence of a magnetic field, say from a permanent magnet, and the lines of flux from the permanent magnet are trapped inside the superconductor causing the superconductor to be held ("pinned") at a fixed...

please help me in cllecting information about High Temperature Superconductor motor. Are they available in the market? how effecient are they? I need to know all their details, properties, design, advanteges. Thanks all

Hey everybody, just wanted to know if anyone had any experience with superconductor fabrication? I know the whole crystal lattice structure thing is more chemistry than physics but I figured I could post in both places. Anyways, I am currenty trying to fabricate a 1-2-3 YBCO superconductor...

hi i have superconductor question, need someone familiar with this field. does anyone know how to prove normalization of bcs equation? <psi|psi>=1 given uk^2 + vk^2 =1 i went through the Heisenberg algebra but still can't solve it. any guide?

in deriving quantization of flux in superconductor ring, the momentum of cooper pair p: p=\hbar\nabla\theta=e^*(\Lambda J_s + A) then integrate around the ring, \hbar\oint\nabla\theta dl=e^*\oint(\Lambda J_s + A)dl using stoke's theorem and integrate sufficiently deep in the ring where...

1. is MgB2 brittle? can we draw it like wire and wind it up make a coil/electromagnet with it? 2. liquid nitrogen boils at 77K and freezes at 63K. most superconductor experiments use liquid nitrogen, so does it mean most applications use this temperature range (eg. for squid)? what about...

Look at this figure. http://img223.imageshack.us/img223/2136/rotatingsuperconductorandmagne.th.png What will happen to the repulsive force between magnet and superconductor?Would the repulsive force increase with rotation?

1. why, instead of cooper pair, don't we have a group of N electrons coupled for superconductivity? 2. Has cooper pair been observed experimentally? 3. What kind of thermometer do we used to measure near 0 K temperature? 4. Has Josephson tuneling for oxyde high Tc been made? Because...

suppose we have a superconductor speciment above Tc, and we put it in magnetic field. then we cool it down to below Tc, then a screening current is produced. where does the electron get the energy to initiate the current on the first time?

I am new to superconductors and how they work. :confused: Could anybody maybe explain how currents actually arise in a superconductor? Is it just by placing the superconductor in a B-field that causes a current due to the expulsion of the external field (Messiner Effect)? If so, is that...

Greetings ! I was wondering how (or if) a superconducor can be connected to a "normal" conductor in an electric circuit ? I guess the conductor-superconductor connection is easy, but how do you avoid problems at the reverse connection - do you need some amplifier or something. Also...

Ok, I can't exactly run out to the store and put some of these in my freezer to experiment with (hurry up guys :smile:), so here's just some questions I was thinking about. - Superconductors would have very near zero resistance (part of their definition) so would that mean that the current...

Why is a superconductor a diamagnet?