Resistance of a metal wire as temperature increases

uses the Phet java applet to show how the resistance of a metal increases with temperature.

[helenday]

Very clear explanation, with a nice colourful video to keep me cheerful; thanks. This chap could do probably with a better microphone though, as the sound is a bit hazy in parts. (I think. I don't know much about microphones, I've just heard about this sort of thing somewhere )

[ignaciomartinez]

Heating a copper wire will change its resistance. As the wire becomes warmer, the valence electrons become more active. They move farther away from the nuclei and they move more rapidly. This activity increases the chance for collisions as current carrying electrons drift towards the positive end of the wire. Theses collisions absorb energy and increase the resistance to current flow. The resistance of the wire increases as it is heated. All conductors show this effect. As they become hotter, they conduct less efficiently and their resistance increases. Such materials are said to have a positive temperature coefficient. This simply means that the relationship between the temperature and the resistance is positive that is they increase together.

[xdnxgrk]

it seems so obvious now that i've watched this!

thanks v much

[pravingurjar]

Cool one got the concept totally cleared just please be a lil louder next time;)

[normanpouch]

Whats the cure. I have a solar system 4 kW during this hot weather 40C plus in the loft, the 2.5mm 3 core cable 15 its long can't cope and the voltage goes up to 256-257 volts inverter cuts out Grid voltage 252-253 so at the limit. If I put cable outside north side house will that help air temp then 34 C max, not over 40C?? many thanks,

[tbone-frtr]

The circuit is not possible because it is purpetual