Question

Question 12:
(a) How does the resistance of a pure metal change if its temperature decreases ?
(b) How does the presence of impurities in a metal affect its resistance ?

Lakhmir Singh Physics Class 10

Answer 1

1. resistance increase as the temperature decrease.

Explanation:

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Answer 2

Explanation:

(a) A positive coefficient for a material implies that with a rise in temperature, its strength improves. Generally, pure metals have a favourable resistance temperature coefficients. An adverse coefficient for a material implies that with a rise in temperature, its strength reduces.

(b) The existence of impurities in a metal affects its strength significantly.  Impurities make the metal extremely resistant.  The more impurities a metal will add, the stronger it will be. So the relationship between the metal and the impurities can be said to be directly proportional.