This question was in our textbook: 'Why does the heating cord of an electric heater not glow while the heating element does glow when electric current passes through it?'.
All I have been taught is alloys do not oxidize readily, hence they are used in common heating appliances like toasters and heaters. I understand that the heating element is made of an alloy which dissipates huge heat due to higher resistance and hence a part of the heat energy transforms to light energy in the heating element. But I am very much confused about the heating cord.
Can anyone please explain me about the heating cord-What is its purpose in an electric heater? And what material is it made of?Any help is appreciated. Please feel free to correct any mistakes.
Best Answer
Courtesy of AnnaV :
By heating cord your book probably means the wire or flex which conducts electricity from the power supply to the heater. This is made of copper because it has very little resistance to current, compared with the resistance of the heating element, which is very high. The electrical power dissipated in a resistance $r$ when current $I$ flows through it is $I^2r$. The same current flows through the wire and the element, but the resistance of the element is very much larger. Very little electrical energy is dissipated in the wire so it does not get hot and does not glow - unlike the heating element.