Discuss the variation of resistance with temperature with an expression and a graph.
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as we know, relation between temperatures and resistance is written by
R = R₀[1 + α(T - T₀)]
Here, R is the resistance at temperature T
R₀ is the resistance at the temperature T₀
α is the coefficient of resistance.
For metal :- if you learnt thermal effect of current , then you must know that resistivity is inversely proportional to time of relaxation. So, resistance is also inversely proportional to time of relaxation. But we know if we increase the temperature , metal atoms vibrates and electrons moves more faster than initially. so, time of relaxation decreases this reason resistance increases.
or, you can say that coefficient of resistance is positive in case of metal .
Graph of resistivity and temperature is shown in figure.
For semiconductor :-in case of semiconductors, coefficient of resistance be negative. so, if we increase the temperature resistance will decrease.
Here groph is shown the relation between temperatures and resistivity of semiconductor.
R = R₀[1 + α(T - T₀)]
Here, R is the resistance at temperature T
R₀ is the resistance at the temperature T₀
α is the coefficient of resistance.
For metal :- if you learnt thermal effect of current , then you must know that resistivity is inversely proportional to time of relaxation. So, resistance is also inversely proportional to time of relaxation. But we know if we increase the temperature , metal atoms vibrates and electrons moves more faster than initially. so, time of relaxation decreases this reason resistance increases.
or, you can say that coefficient of resistance is positive in case of metal .
Graph of resistivity and temperature is shown in figure.
For semiconductor :-in case of semiconductors, coefficient of resistance be negative. so, if we increase the temperature resistance will decrease.
Here groph is shown the relation between temperatures and resistivity of semiconductor.
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