Write a note on the variation of resistance of a metallic conductor with temperature.

Explanation

The resistance of a conductor increases or decreases with the increase or decrease of temperature.
`R=R_(0)(1+alphat+betat^(2)+gammat^(3)+…)` where `alpha,beta,gamma` are called the I order, II order and III order temperature coefficients respectively. However, `beta, gamma`, ............ are far less than `.alpha.`.
Hence `R=R_(0)(1+alphat),` to a near degree of approximation. Electrical resistance varies linearly with the resistance due to collision between electrons and oscillating ions in the lattice.
We can show that `alpha=(R-R_(0))/(R_(0)t)K^(-1)`. Temperature coefficient resistance of a conductor is defined as the ratio of change in the resistance per degree kelvin change in the temperature to its resistance at `0^(@)C` or 273 K.
A graph of resistance along the y-axis and temperature along the x-axis, gives a straight line with ay-intercept `.R_(0).` and slope of the line `.R_(0)alpha.`.
`alpha=(1/(R_(0)))` ) (slope of the line).

The x-intercept on the .-x. axis indicates that the resistance of the conductor vanishes at a temperature called transition or critical temperature. Conductors become super conductors at the critical temperature and below it. The phenomenon of conductors losing all the resistance to the flow of charges at the critical temperature and below it is known as super conductivity.