– How does a rice cooker know when the rice is done?
In: 258
It senses a rise in temperature after water has been absorbed or evaporated. While water is present, the temperature cannot rise above 100° because excess added heat is put into converting the water into steam, which cools off the vessel. After the water is gone, temperature can increase further like on a frying pan.
It depends on 3 things.
1. As a rule of thumb rice is done when all the water is boiled off.
2. When water is boiling it keeps the thing at 100C, any more energy just makes more water turn from liquid to gas.
3. When a magnet gets too hot it gets less sticky.
So they have a magnet that’s holding a electric connection to the heater that cooks the rice.
When you press the cook tab, you hear a clunk, that’s the magnet sticking.
The water in the cooking part with the rice starts boiling, when it’s gone the temperature starts going above 100C.
That temperature makes the magnet less sticky and it falls off, breaking the connection with the cooking parts.
That or it’s a boring temperature sensor and a microchip.
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It’s one amazing piece of ingenuity.
Some magnets lose magnetism at a certain temperature.
The one in the rice cooker lose it at a little above 100 Degree Celcius.
So if water is still in the cooker, the temperature stay at 100 (as any extra energy goes into vaporation instead) only when all water gone that temperature will go above 100, that’s when the magnet “turn off” and prevent your rice from burning.
It’s actually pretty ingenius
Water boils at 100°C. That means that water will never get hotter than that. But if there isn’t water, it can.
So rice cookers have a heat detecting system at the bottom of the pot. (Note, not an electric one. But that’s a story for another comment)
So you put water and rice in, and turn on the heat. The heating filament heats up the water as hot as it physically can (which is only 100°).
Eventually, without water covering the bottom of the cooker, the temperature at the bottom will eventually go over 100°. Once it does, the cooker kills the heat.
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Rice is done cooking when the water evaporates
Water can only get so hot, after that it stays the same temperature until it turns to steam
Rice cooker sees the temperature suddenly goes up
Turns off
No water
Good Rice.
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