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Famous inventions: The microwave

microwaveA melted chocolate bar led American engineer, Percy Spencer, to realise the cooking potential for the microwaves he was researching.

In 1945 Percy Lebaron Spencer, an American engineer and inventor, was busy building magnetrons, the devices used to produce the microwave radio signals that were integral to early radar use. While standing by a functioning magnetron, Spencer noticed that the chocolate bar in his pocket had melted and soon figured out that it was the microwaves that had caused it.

With this in mind, Spencer went on to create a high density electromagnetic field by capturing microwave power inside a metal box. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly. The first food to be deliberately cooked in the microwave was popcorn and the second was an egg which exploded.

The first microwave oven weighed nearly 750lbs and was about the same size as a fridge.