A microwave oven (commonly called a microwave) is a machine that cooks food using microwaves, a type of radio wave. The idea was invented when a scientist who was experimenting with radio waves saw his chocolate bar, which he was holding at that time, melt. He then knew that radio waves could cook food and invented the microwave oven.
How to use a microwave[change | change source]
Metals tend to spark in microwaves, rather than heating. The reason why is that metals like to give away electrons, so when the microwaves "push" at their magnet-like electrons, instead of turning, they just give the electrons away. A bunch of electrons running off on metal is called electricity, and we see it in the form of sparks.
How it works[change | change source]
The microwave oven uses a magnetron. This is similar to a radio transmitter. It makes very short radio waves which go into the food to a depth of about 2.5cm (one inch). This makes water molecules swing to and fro at about 2.5 billion times a second. This heats up the molecules around it. As they heat up the heat goes to the inside of the food. This process is called conduction. This also happens in a normal oven, but microwave energy goes deeper so that the food cooks much faster. In an ordinary oven the energy stays mostly near the surface
Apart from this the oven has a wave guide, turntable, and a timer switch. When we place the food inside the chamber and turn the timer switch on, it sends a command to the magnetron to send microwaves as well as to the turn table to start turning. The microwaves mostly heat food which has water molecules. (Two atoms of Hydrogen and one atom of oxygen make water. H2O). When the oven is started it sends microwaves. These waves go and touch the water molecules. Then the water molecules start vibrating against each other at a very high speed this generates heat. Fats and sugars are heated less than water, and other foods much less. The turntable moves so that the food is heated evenly.
Microwaves can go through fine China Bone, Glass or special plastic materials. Metal such as aluminum foil cannot pass the radiation because when the waves come to it they reflect from it and go away. The microwave oven can be used to cook food or only heat it up.
Related pages[change | change source]
References[change | change source]
- "Teaching the world to ping", The Independent, Thursday 12 May 2011; Viewspaper p.16