Question

Assertion- At high temperatures,metal wires have a greater chance of short circuiting. Reason-Both resistance and resistivity of a material vary with temperature.​

Answer 1

Answer:

Explanation:Metals, including alloys, have free electrons as charge carriers. Their movement controls by defects. One of defects of usual metal is oscillations of atoms due to temperature. More temperature - more oscillations - more collisions of electrons with atoms - less mobility - more resistivity. In alloys, like constantan, atoms are in disorder so alloys have big resistivity. Their additional disorder due to temperature increase is insignificant. That is why alloys have no temperature dependence of resistivity. The same picture is with metal glasses.

Answer 2

At high temperatures,metal wires have a greater chance of short circuiting because of excessive heat produced due to the high resistance to the current.

Explanation:

We have the relation between the variation of resistance and resistivity each with respect to the temperature.

FOR CONDUCTORS:

• $\rho_T=\rho_T'(1+\alpha(T-T'))$

where:

$\rho_T=$ resistivity at temperature T

$\rho_T'=$ measured resistivity at reference temperature T'

$\alpha=$ constant coefficient of resistivity

Similarly

• $R_T=R_T'(1+\alpha(T-T'))$

$R_T=$ resistance at temperature T

$R_T'=$ measured resistance at reference temperature T'

$\alpha=$ constant coefficient of resistance

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TOPIC: resistance variation with temperature

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