Making Waves From Electricity

The magnetron makes waves from electricity

The hidden part is called a magnetron. Cut it open and you see a hot rod in the middle that gives off electrons (the blue dots). Magnets bend their path, so they swirl around in circles. Each time a clump of electrons sweeps past a hole in the copper ring, the hole rings and sends out a wave. These waves wiggle 2.45 billion times a second. A metal pipe carries them into the inner box.

Why?Blow across the top of an empty bottle and it hums. Each puff makes the air inside the bottle ring. The copper holes in a magnetron work the same way: every time the electrons sweep past, the electricity in the hole rings, and the holes are sized to ring 2.45 billion times a second.

Learn moreThese waves are the same kind as radio, phone and Wi-Fi signals. They travel as fast as light but are invisible. They are called microwaves, and the back of the oven usually says “2450 MHz”, which is how often they wiggle. The magnetron runs on thousands of volts, so never open the cover, even when the oven is off.

How often the waves wiggle

2.45 billion a second

textbook formulas · example oven cavity 31.5 × 21 × 32.5 cm