Source: Business Insider
Published: July 2015

From Magnetrons to the Microwave

Circulated: March 26, 2020

In 1945, Percy Spencer was working in a lab testing magnetrons, the high-powered vacuum tubes inside radars. One day while working near the magnetrons that produced microwaves, Spencer noticed a peanut butter candy bar in his pocket had begun to melt — shortly after, the microwave oven was born.

With his newfound knowledge on how to cook food in mere seconds, Spencer and his employer, Raytheon, patented the invention. Two years later, they launched the first commercial microwave oven, which cost $5,000 at the time ($60,000 today) and weighed 750 pounds (340 kg).

By 1986 25% of American households owned a microwave, which rose to 90% in 1997, and 96% in 2012.