# What does a negative temperature coefficient of resistance mean?

• xllx
In summary, a material with a negative temperature coefficient of resistance means that the resistivity will decrease and the conductivity will increase as the temperature increases. This is often seen in semiconductors due to an increase in charge carriers, while metals typically have a positive temperature coefficient of resistance due to increased carrier scattering.
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:
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).

xllx said:
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?

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.

## 1. What is a negative temperature coefficient of resistance?

A negative temperature coefficient of resistance (NTC) means that as the temperature of a material increases, its resistance decreases. In other words, the material becomes more conductive as it gets hotter.

## 2. How is a negative temperature coefficient of resistance different from a positive temperature coefficient?

A positive temperature coefficient (PTC) means that as the temperature increases, the resistance also increases. This is the opposite of an NTC, where resistance decreases with increasing temperature.

## 3. What causes a material to have a negative temperature coefficient of resistance?

The NTC effect is usually seen in materials that have a large number of mobile charge carriers, such as semiconductors. As the temperature increases, these carriers gain more energy and are able to move more freely, leading to a decrease in resistance.

## 4. How is a negative temperature coefficient of resistance used in practical applications?

The NTC effect is commonly used in thermistors, which are electronic devices that change resistance in response to temperature. This makes them useful for temperature sensing and control in various devices and systems.

## 5. Can a material have both a negative and positive temperature coefficient of resistance?

Yes, it is possible for a material to exhibit both NTC and PTC effects, depending on the temperature range. For example, some materials may have an NTC at low temperatures and a PTC at high temperatures.

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