microwaves

Microwaves are electromagnetic waves with shorter wavelengths than radio waves.

Microwaves can pass through the Earths atmosphere

They can be used for communications such as:

• satellite communications

• Mobile phones

Radar

Microwaves reflect from metal objects, they are used in radar. Radar is used to locate objects by measuring the time it takes for microwaves to travel too and from an object.

Ovens

Microwaves with a wavelength of 12cm are absorbed by water molecules.

Microwaves of this wavelength can be used for cooking. The water molecules in food absorb the microwaves, they gain energy and heat up the food.

Microwaves can penetrate to a depth of about 1ccm into food. This cooks small pieces of food from the inside. Although, larger pieces of food rely on conduction to transfer heat further into the food.

Microwaves can pass through plastic packaging without melting it.

Danger

Exposure to microwaves with a wavelength of 12cm can lead to burning since they can be absorbed by water molecules in the body.

Most microwave ovens have a metal grill over the door to reflect back microwaves into the oven to protect users.