Subject: How exactly does resistance cause heat increase?

Hi
I'm doing a scool project on resistance and my question baffaled my 
teacher so I though I'd ask you guys.
While passing a current through a wire, how exactly does electrical energy 
get transfered to kenetic energy to heat up the wire. Some people say that 
the energy is transfered becuase the electrons crash into the nucleus of 
the atoms which make up the wire, but my teacher said that the electrons 
never actually touch the nucleus. If they never touch then how is heat 
produced? Also when the electrical energy is transfered to heat energy do 
the electrons just disappear and if not do they carry on and still produce 
a current.

Re: How exactly does resistance cause heat increase?