This is a how the rice cooker works in a simplified language -
Once the rice and water are placed in the basin, the cooker is switched on after placing the basin into the container. The heating element in the container makes the water to boil and the rice absorbs the boiling water. The steam is locked by the outer lid from escaping out.
The water can be heated upto 100 degree celsius and as long as liquid water is present in the container, it continues to absorb heat while rice will not. Once the all the water is absorbed by rice and no water is left inside, rice begins to heat up. The thermal sensor in the cooker monitors the temperature in the container and when it senses the temperature going beyond 100 degree celsius (which is an indication of all water being absorbed), it automatically shuts off heating mechanism. Thus further cooking is stopped and rice is done.
Live....and Let Live!