How Was Microwave Invented?

OOPS! That’s usually what we say when we have an accident. But sometimes accidents can lead to new discoveries. Dr. Spencer’s little accident led to the invention of Microwave !

spencer and microwave

Here’s how it went down. Dr. Percy Spencer was always a science whiz. He was an American physicist, inventor, and radar engineer. He was mostly self-taught and very curious about the world around him.

Dr. Spencer learned a lot from his various jobs. When he was younger, he worked at a paper factory. There, he learned about electrical wiring and helped the plant run on electricity. When he was 18, he joined the U.S. Navy. That’s where he trained himself in wireless and radio technology. After that, he worked at a company called Raytheon. The company specialized in technology and electronics.

And that’s where his miraculous “accident” took place. One day, while working at the plant, Dr. Spencer was testing magnetrons. Everything seemed pretty normal. Until suddenly, he felt a sizzling sensation in his pocket. When he checked it out, he noticed his candy bar had melted!

What is a magnetron?


A magnetron is a technical instrument that creates a power or a force. It is made up of a metal rod (cathode) surrounded by a ring (anode). When a powerful magnet is turned on, the electrons moving around in the instrument will flow in a predictable way. The resulting power from this flow can be used for radar equipment, or even for Dr. Spencer’s awesome invention.


Dr. Spencer was amazed. He was very curious why the magnetron had melted the candy. And if he could melt candy, what else could he do? He decided to conduct a few experiments to find out.

He tried using different foods. He stood near the active radar set holding a bunch of unpopped kernels of corn. And guess what happened? The kernels began to pop! Soon, popcorn flew in every direction.


Then his mind began to race. What if he could create a machine that could cook food quickly? At the time, this was a foreign concept. People used stoves, but they were very slow.

After his discovery, Dr. Spencer began to design prototypes. In 1947, he created the first commercial microwave. It was massive. It was 6 feet tall and weighed about 750 pounds! It cost about $5,000 and was mostly used in restaurants, on trains, and on ships.

microwave then and now
It was too bulky and expensive for homes. But as the years went by, the model evolved. Today, most families have a microwave in their kitchen. And imagine - this amazing discovery came about because Dr. Spencer accidentally melted a candy bar in his pocket.

So the next time you have an “accident,” remember that it may be an opportunity to make an awesome invention or at least learn something!

Article was originally published in Smore issue #5 May – June 2018


Copyright @smorescience. All rights reserved. Do not copy, cite, publish, or distribute this content without permission.

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