How do ovens work?

Answer 1

1. Conventional ovens generate heat using up to two heating elements, one on the top of the oven (used for broiling) and one on the bottom of the oven (used for baking and roasting). These heating elements may be fueled by natural gas or electricity. In gas ovens, the user can see blue flames around rod-like heating elements; in electric ovens, coils snaking along the top and bottom of the oven turn bright red as they heat up. Regardless of how an oven is heated, inside the oven it will always be hotter on the top than it is on the bottom. This is called natural convection (hot air rises, and cold air sinks) and requires oven users to sometimes rotate the food as it bakes or roasts.
2. Controls on the outside of a conventional oven are manual or computerized. Either way, an oven user must set an oven's thermostat to a particular temperature to turn the oven on. To turn the oven off, the user sets the temperature to zero degrees. (This is usually marked as "Off" on the oven's controls as well.) Some computerized ovens come with timers; users can then tell the oven when to turn on and at what temperature, as well as when to shut off.
3. Broiling often means that only the top heating element is turned on. When broiling with an electric oven, a user must keep the oven door open a crack to fool the thermostat. If the door is kept closed, the oven will heat up to around 500 degrees and automatically shut off (a common safety feature). When using a gas oven to broil, a user must first determine if the broiling heating element is on the top of the oven (like it is in electric ovens) or if the only heating element is on the bottom of the oven, in which case a drawer will open beneath the oven, revealing a broiling rack very close to the floor. When broiling using a gas oven, the door may be closed.
4. Self-cleaning ovens oxidize the dirt inside them by heating up to around 900 degrees. The oven door automatically locks while the oven is cleaning itself to prevent a curious oven user from opening the door and being burned. A self-cleaning cycle can last up to 3 hours, and the oven door is automatically unlocked when the oven returns to a safer temperature (usually below 600 degrees). Ovens that offer this convenience are better insulated than those that don't.

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