Bimetal / Strip

Two metal strips of the same length but with different coefficients of thermal expansion are joined together and fixed at one end. When the temperature increases the bimetal strip bends into the direction of the metal with the lower coefficient of thermal expansion. When the temperature decreases the bimetal strip bends into the direction of the metal with the higher coefficient of thermal expansion. Due to this moving behaviour bimetals are used in many devices and instruments, as e.g. thermometers, thermostats (temperature measurement/control); electric kettles, relays (overheat protection, circuit breaker).