JEE MAIN - Physics (2002 - No. 25)
By increasing the temperature, the specific resistance of a conductor and a semiconductor
increases for both
decreases for both
increases, decreases
decreases, increases
설명
Specific resistance is resistivity which is given by
$$\rho = {m \over {m{e^2}\,\tau }}$$
where $$n=no.$$ of free electrons per unit volume and $$\tau $$ $$=$$ average relaxation time
For a conductor with rise in temperature $$n$$ increases and $$\tau $$ decreases. But decrease in $$\tau $$ is more dominant than increase in $$n$$ resulting an increase in the value of $$\rho $$
For a semiconductor with rise in temperature, $$n$$ increases and $$\tau $$ decreases. But the increase in $$n$$ is more dominant than decrease in $$\tau $$ resulting in decrease in the value of $$\rho .$$
$$\rho = {m \over {m{e^2}\,\tau }}$$
where $$n=no.$$ of free electrons per unit volume and $$\tau $$ $$=$$ average relaxation time
For a conductor with rise in temperature $$n$$ increases and $$\tau $$ decreases. But decrease in $$\tau $$ is more dominant than increase in $$n$$ resulting an increase in the value of $$\rho $$
For a semiconductor with rise in temperature, $$n$$ increases and $$\tau $$ decreases. But the increase in $$n$$ is more dominant than decrease in $$\tau $$ resulting in decrease in the value of $$\rho .$$