How resistivity of material depend on temperature. Write empirical formula .

Explanation

`rArr` Resistivity or material depend on temperature. Different material have different dependence on temperature.
`rArr` Resistivity of metal increase with increase in temperature.
`rArr` Resistivity of semiconductor decrease with increase in temperature.
`rArr` Over a limited range of temperature that is not too large the resistivity of metallic conductor is approximately given by.
`rho_(T) = rho_(0) [1 + alpha (T - T_(0))] `
`rho_(T)` = resistivity at temperature T
`rho_(0)` = resistivity at reference temperature `T_(0)`
`alpha` = temperature coefficient of resistivity
`rArr` Resistivity of same metals is given in table shown below.
`rArr` For metals value of `alpha` is positive.
`rArr` For semiconductor `alpha` is negative.
` rArr` For some metals value of `alpha` at `0 ""^(@) C` is shown in table below.