Superconductors and the Meissner effect

In summary, the conversation discusses the Meissner effect, a phenomenon that occurs in superconductors when an external magnetic field induces a countercurrent, causing the magnet to levitate. However, there is conflicting information on how this effect is actually produced. Some sources state that it is due to quantum locking in type II superconductors, while others argue that it is a result of induction in a perfect conductor. The Wikipedia page on the Meissner effect provides a more comprehensive explanation, highlighting the difference between induction and the active expulsion of a pre-existing magnetic field in superconductors.
  • #1
Rizke
5
1
So I am writing a paper on superconductors, and i am trying to explain the meissner effect. However i seem to be running into conflicting information. I hoping some one can help clarify.

The effect happens, when a magnet creates a change in flux, causing a induced current in the superconductor. This current produces a induced magnetic field that is opposite from the original. this repulsiveness let the magnet float or "levitate"
But if the magnet is just resting at right before critical temperature, how is there a change in flux.

Others state, the in type II superconductor, they reach a state in between two critical fields, which trap some magnet flux lines with in. This quantum locking, locks the magnet in place.
 
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  • #2
The first effect you describe, i.e. where an external magnetic field sets up a countercurrent in the superconductor is, to my understanding, actually not the Meissner effect. It's just a consequence of induction in a perfect conductor.
The Meissner effect on the other hand actively expels a pre-existing magnetic field when the conductor becomes superconducting. That you can't explain with plain induction, and it apparently has much more complex causes.

The Wikipedia page on the matter is pretty good, and there they point out that bringing a magnet close to a superconductor does not show the Meissner effect because it just is causing the induction effect. However, having an already close magnet start levitating after cooling down the conductor, that shows the Meissner effect.
 

What is a superconductor?

A superconductor is a material that has zero electrical resistance and can conduct electricity without any energy loss when it is cooled below a certain temperature, called the critical temperature. This phenomenon is known as superconductivity.

How does the Meissner effect work?

The Meissner effect is a property of superconductors where they expel any external magnetic field from their interior when they are cooled below their critical temperature. This is due to the formation of supercurrents within the material that create a magnetic field that cancels out the external field.

What are the practical applications of superconductors?

Superconductors have many practical applications, including in medical imaging devices such as MRI machines, in high-speed trains and maglev trains, and in particle accelerators. They also have potential uses in energy storage, power transmission, and quantum computing.

What is the critical temperature of a superconductor?

The critical temperature of a superconductor is the temperature at which it transitions from a normal conducting state to a superconducting state. The critical temperature varies for different materials and can range from a few Kelvin to over 100 Kelvin.

How are superconductors made?

Superconductors are typically made by mixing and melting together different elements to form a compound, which is then cooled to a specific temperature to induce superconductivity. The critical temperature of a superconductor can also be enhanced through various methods such as adding impurities or applying pressure.

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