Electric current is the result of moving free anions, cations or electrons, as we have seen. When there is electric current, the particles that are moving end up colliding with the other parts of the conductor that is at rest, causing an excitation that will generate a heating effect. This effect is called the Joule effect.
The heating in the wire can be measured by the joule law, which is mathematically expressed by:
This relationship is valid as long as the current intensity is constant over the time interval of occurrence.