Electric Current Density.

Electric current's density J depends on electric current's intensity I measured in (A) & on conductor wire's gauge S measured in mm².

It is described by a physical formula:

J = I / S,

where:
- J is electric current's density, measured in A / mm²,
- I is electric current's intensity, measured in A,
- S is conductor wire's gauge, measured in mm².

As electrons flow between two points with different electric potential (amount of electrons & positrons in an atom), physical medium resists their flow & gets heated.

Amount of heat depends on:
- conductor wire's gauge, measured in mm² - in thinner conductor wires electrons flow faster & there's more heat,
- electric intensity - the more amperes the more heat,
- conductor wire's material - the more resistance the more heat.

it's all not so simple outside wired circuits, however.