# What does a negative temperature coefficient of resistance mean?

1. Feb 12, 2009

### xllx

If a material has a negative temperature coefficient or resistance, what does this mean?

Does it mean that as temperature increases, the resistance will increase instead of decrease.
Or something totally different?

Any help at all would be greatly appreciated! Many Thanks!

Last edited: Feb 12, 2009
2. Feb 12, 2009

### mgb_phys

Other way round.
The conductivity increases with temperature, ie resistance decreases.

In general, electrical resistivity of metals increases with temperature (+ve), resistivity of semiconductors decreases with increasing temperature (-ve).

3. Feb 12, 2009

### Mapes

It means that the resistivity will decrease (or the conductivity will increase) with an increase in temperature. This is a common feature of semiconductors, because the number of charge carriers increases strongly with temperature. In metals, conversely, the number of charge carriers isn't strongly dependent with temperature. Instead, the dominating effect is increased carrier scattering with temperature. This results in a positive temperature coefficient of resistance: increased resistance due to a temperature increase.