The microwave oven was invented after chocolate was melted by a radar.

True. The microwave oven was invented by pure chance. In 1945, Percy Spencer, an engineer at Raytheon, was working with an active radar when he noticed a chocolate bar in his pocket had melted, even though it wasn't near any obvious heat source. His curiosity led to experiments, including with corn kernels (resulting in the first microwave popcorn!), and later to the invention of the microwave oven, which revolutionized cooking worldwide.