why metals have positive temperature coefficient for resistance/?

Question

Since for metals as the temprature increases the resistivity decreases.

Answer 1

In metals the number of carriers (free electrons) remains constant, and independent of temperature. But mean free path of each electron decreses with temperature, because atoms forming the lattice vibrate more strongly.

The latter statement is kind of hard to explain without quantum mechanics, because, as it turns out, if atoms stop vibrating, then electrons will not scatter on them at all, strange as it sounds.


Unlike in metals, in semiconductors the density of carriers (electrons and holes) increases exponetionally with temperature, much faster than theirr scattering. For this reason semiconductors, unlike metals, have negative temperature coefficient of resistance.

Answer 2

Temperature Coefficient Of Resistance

Answer 3

Positive Temperature Coefficient

Answer 4

In metals resistance increases with temperature:

- Higher temperature means more energy is transferred to the positive ions in the metal lattice.
- Hence the ions vibrate more.
- Hence the electrons flowing through the metal are more likely to collide with the ions and transfer some of its kinetic energy to the ion causing them to vibrate even more, and raising the temperature even more.
- Hence resistance against the electron flow increases with temperature.

Answer 5

Don't think yougot that one right. Metals tend to get more disordered with temperature increase so resistance goes up.

Answer 6

as temperature increases resistivity decreases for metals.

Answer 7

Sure about that?

Copper, for one, has a positive temperature coefficient of resistance. The resistance of copper doubles when you raise it by 390.1F from room temperature.
.