Kettle PNG
After pressing the button, a large electric current flows through the coil. Electric current is formed in the conductive material by the movement of electric charge as a result of potential difference.
The coil has an electrical resistance. This resistor converts electrical energy into heat as it passes through the coil.
The water that comes into contact with the heat emitted from the resistance is heated by convection. Thus, the water in the heater comes to the boiling point.
Some kettles use a thermostat that turns it off when the water reaches the right temperature.
Most automatic kettle designs are based on designs developed by British inventor John C. Taylor, whose companies Otter Controls and Strix Ltd have developed more than a billion such thermostats worldwide.
The simplest operating methods of these thermostatic water heaters are mechanical. It works with a bimetallic thermostat integrated into the element unit below the kettle. This thermostat consists of a disc of two tightly bonded dissimilar metals, one of which expands faster than the other as the temperature rises. Normally the thermostat bends in one direction, but when the hot water reaches its boiling point, the steam produced hits the bimetallic thermostat and suddenly flutters and twists in the opposite direction, like an umbrella in the wind. When the thermostat opens, it pushes a lever that opens the circuit, shutting off the electrical current and safely shutting down the kettle. More sophisticated kettle thermostats are electronic, turning the current on and off repeatedly, allowing water to be heated to precise temperatures and held there indefinitely.
