It was thought that the electrical resistance of a conductor becomes zero only at absolute zero temperature. But in 1911, H. Kammerlingh Onnes, studied that the properties of mercury at very low temperature using liquid helium. He found that the resistivity of mercury drops to zero at 4.2 K and changes into a superconducting material.
Mathiessen’s rule
Definition
The ability of certain metals and alloys exhibit almost zero electrical resistivity, when they are cooled to low temperature. This is known as superconductivity. (ie., maximum conductivity with zero resistance at zero Kelvin)
The superconducting state is defined by three very important factors: critical temperature (Tc), critical field (Hc), and critical current density (Jc). Each of these parameters is very dependant on the other two properties present.
Critical temperature (Tc )
The highest temperature at which superconductivity occurs in a material. Below this transition temperature Tc the resistivity of the material is equal to zero.
Critical magnetic field (Hc)
Above this value of an externally applied magnetic field a superconductor becomes nonsuperconducting.
Critical current density (Jc)
The maximum value of electrical current per unit of cross-sectional area that a superconductor can carry without resistance.
| Read More Topics |
| Charge densities in a semiconductor |
| Electrical conductivity in intrinsic semiconductor |
| Mobility and conductivity in semiconductors |
