Franklin is probably most famous for his kite experiment. As the story goes, he and his son flew a silk kite on a long cord when the sky was full of black clouds.
A metal rod was tied to the kite. An iron key was attached to the end of the cord. Franklin and his son tied a silk string to the end of the cord, where the key was, and held on to that.
As storm clouds approached, the metal rod drew electricity, which Franklin called “electric fire,” from them. When rain got the kite and the cord wet, that electricity was conducted from the rod to the key. That’s because water is a good conductor of electricity. Franklin touched the key with his knuckle and felt an electrical shock. This proved his theory that lightning was a form of electricity.