If a resistor is
placed in an electric circuit, it may produce two kind of phenomena:
- The resistor has an influence on the electric current (the higher the
resistance is, the lower the current is).
This influence on the current is used in many electrical appliances and
electronics to modify the electric current. They serve to protect
electric components that do not support too high currents.
In this case the resistor serves to regulate the electric current.
- A resistor traveled by an electric current gives rise to the Joule
By definition the Joule effect is the transformation of electrical
energy received by the resistor into thermal energy.
A resistor traversed by a current starts to heat up. This can be
annoying and unwanted in some cases but it can be harnessed to produce
heat. Thus we find resistors in electric ovens, electric heaters, hair
dryers, irons etc.