- CONDUCTORS– Materials that conduct electricity whenever a supply is provided.
- SEMICONDUCTOR– Materials that can be used as conductors and insulators according to variations in input. The conductivity of semiconductors can be regulated by providing particular inputs.
- SUPERCONDUCTOR– Materials which has gained no resistance conductivity are called superconductors. A superconductor is a metal that acts strangely when cooled down to a specific temperature. When these materials reach their critical temperature they suddenly become perfect conductors.
- Superconductors are separated into two main categories: low-temperature superconductors (LTS), also known as conventional superconductors, and high-temperature superconductors (HTS), or unconventional superconductors.
- Room-temperature superconductors would allow for the electrical transmission of energy with no losses or waste, more efficient maglev trains, and cheaper and more ubiquitous use of MRI technology.
SUPERCONDUCTIVE MATERIALS:
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- Superconductors repel external magnetic fields.
- In a superconductor, the internal induced currents mirror and oppose the external field that would have penetrated the superconducting material. This allows superconductors to expel magnetic fields from their internal volume, except for a thin penetration depth. This phenomenon is known as the Meissner effect.
Meissner Effect
Meissner and Ochsenfeld in 1993 Observed
- When Superconducting Material at temp. T>Tc, is place in ext. magnetic field, lines of magnetic induction pass through its body, but when it is cooled below the critical temp. i.e., T<Tc, these lines of induction are pushed out of the superconducting body.
- So, inside the SC body B=0
- This is Known as Meissner Effect, which is the characteristic property of a superconductor.
Types of Superconductor
Nicholas Gerbis says there are two main types of superconductors. They are classified according to how they react in a magnetic field. The two types are
Type 1: These are usually made of pure metal.
- When it is cooled below its critical temperature it exhibits zero resistivity and displays perfect diamagnetism. This means that the magnetic fields cannot penetrate it while it is superconducting.
Type 2: These superconductors are usually alloys and their diamagnetism is more complex.
- All superconductors have a critical magnetic field. This is the field that either makes or breaks its superconducting state. Type 1 superconductors change states of matter once at one threshold. Type 2 superconductors can change states twice at two different magnetic field thresholds.