Hi,

In this video 

they explain how the resistance in the resistor changes depending on the temperature and you can therefore calculate the temperature. I wonder why the resistance change depending on temperature.

When a metal is heated the atoms vibrate faster.  This faster vibration can impede the smooth flow of the electrons free to flow through it. (afaik).

 

Just looked it up:  https://www.quora.com/Why-does-the-resistance-of-a-conductor-increase-with-an-increase-in-temperature

 

Although the electrons move faster...  so do the molecular vibrations, causing more collisions with the electrons...  so kinda like I said.  There is probably a more detailed explanation somewhere, but that's all I got for now.  

 

 

In quantum terms, those vibrations DrP mentions are described as 'phonons'.

Quote

....thermal vibrations in a solid are a swarm of microscopic particles called phonons. The electrons are trying to drift toward the positive terminal of the battery, but the phonons keep crashing into them. The random direction of these collisions disturbs the attempted organized motion of the electrons against the electric field. The deflection or scattering of electrons with phonons is one source of resistance. As temperature rises, the number of phonons increases and with it the likelihood that the electrons and phonons will collide.

https://physics.info/electric-resistance/

 

Consider there is PTC -positive temperature coefficient-  and NTC -negative temperature coefficient- devices/probes

4 hours ago, Carl Fredrik Ahl said:

 I wonder why the resistance change depending on temperature.

 

Metals normally have a positive temperature ceofficient, semiconductors a negative one but may be doped to be different.

Were the explanations enough or would you like more?

Perhaps including some simple mathematics.

19 hours ago, DrP said:

When a metal is heated the atoms vibrate faster.  This faster vibration can impede the smooth flow of the electrons free to flow through it. (afaik).

 

Just looked it up:  https://www.quora.com/Why-does-the-resistance-of-a-conductor-increase-with-an-increase-in-temperature

 

Although the electrons move faster...  so do the molecular vibrations, causing more collisions with the electrons...  so kinda like I said.  There is probably a more detailed explanation somewhere, but that's all I got for now.  

 

 

Thx for the answer!