how the cooker works?

A rice cooker or rice steamer is a self-contained electrical appliance, used primarily for cooking rice. There are also microwave, gas, and open flame variants.

Basic principle of operationThe bowl in the rice cooker is usually removable, and beneath it lie a heater and a thermostat.These form the main components of the rice cooker. A spring pushes thethermostat against the bottom of the bowl, for good thermal contact toensure accurate temperature measurement. During cooking the rice/watermixture is heated at full power. The temperaturecannot go above the boiling point of water -- 100C (212F) -- as anyheat put into the rice/water mixture at that point will only cause thewater to boil.At the end of cooking some of the water will have been absorbed by therice and the rest is boiled off. Once the heating continues past thispoint, the temperature exceeds the boiling point. The thermostat thentrips, switching the rice cooker to low power "warming" mode, keepingthe rice no cooler than approximately 65C (150F). Simple ricecookers, like the one below, may simply turn off at this point.

圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/9/96/Rice-cooker.jpg/180px-Rice-cooker.jpg