How Do Microwave Ovens Work?
In a microwave oven, you can cook a hamburger in only four minutes. Conventional ovens cook food by heating air which, in turn, heats the food. Microwave cooking is direct. It cooks by creating heat inside the food.
Microwaves are pulses of electromagnetic energy which are beamed into food by an electronic tube. As microwaves pass through food, tiny molecules of moisture in the food rub against each other, causing friction.
This creates heat – the heat which cooks the food. Rub your hands together quickly, and you’ll feel the same “friction heat.”
But how does a microwave turn electricity into heat?
Inside the strong metal box, there is a microwave generator called a magnetron. When you start cooking, the magnetron takes electricity from the power outlet and converts it into high-powered, 12cm (4.7 inch) radio waves.
The magnetron blasts these waves into the food compartment through a channel called a wave guide. The food sits on a turntable, spinning slowly round so the microwaves cook it evenly.
The microwaves bounce back and forth off the reflective metal walls of the food compartment, just like light bounces off a mirror.
When the microwaves reach the food itself, they don’t simply bounce off. Just as radio waves can pass straight through the walls of your house, so microwaves penetrate inside the food. As they travel through it, they make the molecules inside it vibrate more quickly.
Vibrating molecules have heat so, the faster the molecules vibrate, the hotter the food becomes. Thus the microwaves pass their energy onto the molecules in the food, rapidly heating it up.