Five Microwave Facts

A common myth surrounding microwaves is that you can not put metal in them. The walls of the microwave are metal. You put metal in when you cook things like hot-pockets in those sleeves they come with (lined with aluminum, which heats up and browns the crust via convection). Some even come with a metal rack for double deck cooking.

A microwave oven’s radiation does not cause cancer, because it is not ionizing radiation. Even mice that spent their whole lives exposed to low levels of microwaves at the same frequency as a microwave oven, showed no adverse effects from the microwaves.

Devices like your wireless router, GPS satellites, Bluetooth devices, and smart phones also likely operate using the same band as your microwave oven. This is also why when you run your microwave, you may notice those wireless devices stop working well when you get too close to the running microwave. Some fractions of the microwaves from the magnetron are escaping and interfering with the signal your devices are using. The amount is too miniscule to be noticed or felt if you stand in front.

There is nothing special about the material the window of your microwave is made of. It is typically just plastic or glass. What stops the microwaves from cooking you is the metal mesh that is on the inside of the plastic or glass. The holes in the mesh are smaller than the wavelengths of the electromagnetic radiation your microwave is producing. The microwaves bounce off and back into your microwave oven to heat the food.

Many microwavable foods have a recommendation that you let the food sit for a few minutes before eating it. This is because sometimes the food is very thick and the microwaves may not have managed to penetrate deeply and so the center may not be warm, but is surrounded by a very hot outer layer. By waiting a few minutes, it allows the hot part to warm the center and the overall temperature of the food evens out. This is also why when you click “defrost” on your microwave you hear it periodically kicking on and off. It heats the frozen object for a short period and then lets the heated part warm the inner part by convection.