I imagine another reason why rice specifically is the physics behind it. Water has a property where it won't get hotter than it's boiling point while it's boiling.
The way they cook rice is: put rice and water in a pot, boil water until there's no water left, take it off the heat. Because of that property, making a rice maker is extremely cheap. It's just a heating element and a thermostat that switches the element off when the temperature is 101 degrees C (because while there's water, it will only ever be 100 degrees C).
The way they cook rice is: put rice and water in a pot, boil water until there's no water left, take it off the heat. Because of that property, making a rice maker is extremely cheap. It's just a heating element and a thermostat that switches the element off when the temperature is 101 degrees C (because while there's water, it will only ever be 100 degrees C).