Final answer:
An electric heater transforms electrical energy into thermal energy, using the resistance of its heating elements to produce heat through the electronic collisions within the conductor.
Step-by-step explanation:
An electric heater converts electrical energy into thermal energy. This conversion happens when electric current flows through a resistive material in the heater elements, causing the resistance to produce heat. This process is similar to how electrical energy is converted in other household appliances or circumstances, such as the undesired effect in a short circuit, where a large amount of power is dissipated as heat due to a very small resistance, posing a risk of melting or igniting nearby materials.
The electric heater's operation is a deliberate application of the principle that running electricity through a conductor increases the kinetic energy of the electrons, which is then transferred into thermal energy due to collisions within the conductor's lattice structure.