About 60 years ago, radar equipment contained magnetrons, which were vacuum tubes that created microwave radiation.
By HCRS Home Labor Page – https://commons.wikimedia.org/wiki/File:Magnetron2.jpg
Dr. Spencer, who was famous for his research in using radar to find German submarines, visited a laboratory where the tubes were being tested. As he neared the tubes, the chocolate bar in his pocket melted! Surprised, he placed popcorn kernels near the tubes and the kernels exploded all over the lab.
The next morning Dr. Spencer brought in an uncooked egg. He made a pot with a hole in it to cook the egg, and placed a magnetron next to the hole. A curious engineer came over to watch. As he did, the egg exploded in his face! Don’t try that at home! The yolk had cooked faster than the outside, causing the egg to burst.
Dr. Spencer realized that he had “invented” a faster way to cook food—the microwave. He took out a patent on it, which was just one of his over 150 patents.
The first microwave, called the RadarRange, weighed 750 pounds! Here’s one that was on a naval ship.
