Explanation:
Electrical energy is defined as the energy flowing through a device due to the flow of electrons or charges from one point to another.
The energy present within an object or material due to the sum of its motion and potential energy is known as mechanical energy.
Thermal energy is defined as the energy present within an object because of the motion of its particles.
So, when we plug in and turn on a hair dryer then electrical energy starts to flow. As a result, some of its molecules will gain kinetic energy and some will have potential energy.
Hence, its sum will lead to formation of a mechanical energy. Since, this mechanical energy gets converted into thermal energy due to which hairs get dry.
Thus, we can conclude that the energy transformation that occurs when a hair dryer is plugged in and turned on is that electrical energy transforms into mechanical and thermal energy.