[Physics] why do coiled wire create so much heat

experimental-physicsthermal-radiationthermodynamicsthermoelectricity

I am wondering how coiled wire creates so much heat when a current is passed through it. Is it just a larger surface area of heated substance is available or are interacting forces at work eg magnetic and electric fields interacting?
Does adding more coils simply add more surface area or are there more interacting forces as well.

Best Answer

I'm not sure I understand what you're asking exactly, but there are two effects you might be seeing:

  1. A coiled wire is longer than a straight wire that fits in the same space. Therefore it has higher resistance ($R=\rho\dfrac{l}{A}$) and so produces more heat from the same current flowing through it.

  2. A coiled wire can't cool itself as efficiently as a straight wire because radiation from one part of the wire can impinge on another part of the wire instead of out into space; and because air flowing over one part of the wire might then flow past another part of the wire instead of away from the wire.

Related Question