An electric heater is an electrical device that converts an electric current into heat. The heating element inside every electric heater is an electrical resistor, which works on the principle of Joule heating.
Electric heaters are equipped with heating elements that act as electrical resistors. When current is passed through the resistor, heat is produced, thus allowing the heater to increase the ambient temperature. Most electric heaters have heating elements that are made of nichrome wire.
The principle of Joule heating states that an electric current passing through a resistor will convert that electrical energy into heat energy. This is why electric heaters are also known as resistance heating units.
When you turn a heater on, the electrical current that is produced heats up the nichrome wire components — better known as the heating coils — in the unit. Electrical energy is turned into heat as the current passes through the resistor.
The next step in the heating process depends on whether or not the heater has a built-in electric fan or not. If there is a fan, it will help draw cold air into the heater. The air passes over the heating elements and then is pushed out into the room — this is similar to how hair dryers work. This is also known as convection heating because the warmth is transferred through the air.
If there is no fan in the heater, air enters the unit from below. The air flow passes over the coils, is heated and finally finds its way out through the top of the device. This style of electric heating is known as radiant heating — think of a conventional electric stove with a heating element.
In conclusion, an electric heater works by converting electrical energy into heat energy using a resistor. The heat is then transferred to the air either through convection or radiant heating, depending on whether or not the heater has a built-in fan.