Although it makes a great story, Ben Franklin didn't actually discover electricity by attaching a key to a kite during a thunderstorm in 1752. In reality, electricity had already been discovered years before. Franklin himself became interested in electrical phenomenon in 1746, and his kite experiment was merely trying to prove that lightning was electrical in nature [source: The Franklin Institute].
Another myth is that the kite was struck by lightning during the experiment, giving Franklin a powerful shock. This did not happen, and if it had, Franklin very likely would have been killed. Instead, he observed that the fibers on the kite string stood up and the metal key made signs of attracting a charge. It was obvious that the storm clouds were attempting to discharge electricity to an object connected to the ground.
While Franklin didn't discover electricity with his experiment, he did discover what he needed to know in order to invent the lightning rod. The actual purpose of a lightning rod is to provide a path of least resistance from the air to the ground for electricity to travel through. If a lightning bolt strikes a building, it tries to find any way it can to reach the ground, which can result in power surges and possibly even start a fire. If lightning strikes a building with a lightning rod attached, however, the discharged electricity will flow through it and then into a shielded aluminum or copper wire that connects to an underground grid nearby. Rather than attracting electricity, the rod diverts its flow away from the building and its internal circuits, giving it a path directly into the ground with as little damage as possible.
The lightning rods that Franklin invented went on to become wildly popular fixtures on tall buildings in colonial America, and thousands of lightning rods still serve the same important purpose today.
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