Every time I cook rice, I ask myself this question. Today I looked it up.
I figured that it would have some sort of sensor to measure the temperature and/or maybe the humidity… but what exactly does it measure?
Well! It has to do with water not getting hotter than 100 degrees Celsius. So once all the water is absorbed by the rice (which means that the rice is done!) the temperature in the inner pot will start to get hotter than 100 degrees (because rice can become hotter). The rice cooker’s thermometer measures that and triggers the cooker to switch off.