The addition of a component in an electric circuit creates an opposition to the displacement of electrons. This opposition constitutes a load which transforms electrical energy into mechanical energy, light energy, or others.
Resistance reduces the quantity of transformable energy by lowering the voltage and the total current available. It is wasteful in some cases, like corrosion on battery terminal, or useful like in a variable speed controlled fan. In this module, we will look at the usefulness of resistances and their impact on series and parallel electrical circuits.