The working principle of the heater:
At the heart of the heater principle is energy conversion, the most widespread of which is the conversion of electrical energy into heat.
For example, an electric heater uses metal to generate eddy currents in an alternating magnetic field to absorb heat itself, which is converted into light energy;
For example, a solar water heater that absorbs solar radiant heat energy and sunlight light energy (photoelectric effect) into heat energy. Both; bioenergy is an energy stored in the form of chemical energy by a living organism, which is directly or indirectly derived from the photosynthesis of plants.
In addition, there are nuclear energy, wind energy energy conversion modes, but generally need to be converted into electrical energy use.