Benjamin Franklin was one of the founding fathers of the United States. He was also a prolific inventor and scientist who made important discoveries in the fields of electricity, meteorology, and more. One of Franklin's most famous experiments involved using a kite to demonstrate the nature of electricity and lightning. This innovative experiment would lay the groundwork for Franklin's later discoveries about electricity and help revolutionize electrical wiring as we know it.
Franklin's Early Fascination with Electricity
Even from a young age, Benjamin Franklin was fascinated by the natural phenomenon of electricity. In the 18th century, electricity was still a mysterious force that scientists were just beginning to study and understand. As a curious intellect, Franklin eagerly studied static electricity, reading all he could find about early electrical experiments and discoveries made by scientists before him.
He became particularly interested in the Leyden jar, an early version of a capacitor that could store static electrical charges. Franklin procured his own Leyden jar and began conducting experiments on his own to learn more about how electricity behaved. As he experimented with static charges, he developed an analogy between electrical fluid and common water, envisioning electricity as a type of transferable fluid that could flow from one body to another. This fluid model would inform much of Franklin's later thinking and experimentation with electricity.
Learning About Electricity from Lightning Storms
As a young printer in Philadelphia, Franklin observed frequent electrical storms and became fascinated by lightning. Like many others at the time, he theorized that lightning itself was an electrical phenomenon. Other prominent scientists, like Isaac Newton, had also speculated that lightning was electrical, but no one had yet proven this connection empirically.
Eager to test his hypothesis, Franklin devised an experiment that would allow him to gather evidence about the electrical nature of lightning by using a kite during a storm. He proposed that a kite with a pointed wire attached could draw an electrical charge down from the clouds if it was struck by lightning. By flying a kite with a key attached during storms, he would be able to use the key to transfer the electricity down the wet kite string and store a charge in a Leyden jar. This would allow him to capture and study the electricity from lightning.
Flying a Kite in a Lightning Storm
In June of 1752, Franklin decided it was time to test his idea. With the help of his 21-year-old son, William Franklin, he constructed a kite using a large silk handkerchief for the main sail and a pointed wire tip. Franklin believed that the wet string would serve as a conductor to bring electric current down the kite string. He attached a metal key to the bottom of the string in order to store electrical charge in a Leyden jar.
By official accounts, Franklin and his son waited for an approaching storm and then went out into an open field to fly the kite, allowing the string to become damp in a downpour of rain. As the storm picked up, Franklin noticed the loose fibers on the string started to stand on end, signifying they were electrically charged. He then touched his knuckle to the key and felt an electric spark, confirming that his kite experiment was working.
The experiment brought down actual electrical current from the lightning storm, allowing Franklin to capture it in a Leyden jar. This provided concrete evidence that lightning was indeed electrical in nature, proving Franklin's theory correct.
Revolutionizing Understanding of Electricity
Franklin's successful kite experiment helped establish electricity as a distinct scientific field of inquiry and overturned misconceptions about the nature of lightning. His hands-on empirical demonstration that lightning behaved just like the static electricity produced in laboratories was a landmark discovery that shaped modern physics.
By establishing lightning as an electrical force, Franklin helped shift thinking on electricity from speculation to application. His findings formed a basis of knowledge that allowed him to make his later discoveries advancing the practical uses of electricity. After the kite experiment, he invented the lightning rod, discovered electrical charge in clouds, pioneered the single fluid theory of electricity and more.
Overall, Franklin’s humble yet ingenious experiment using a kite and key helped reveal the principles of electricity and lightning. This breakthrough would pave the way for harnessing electricity as a useful force, ultimately helping to revolutionize electrical wiring and technologies. Franklin proved that with creativity and persistence, major scientific advances could come from simple, carefully controlled experiments.
Practical Applications for Electrical Wiring
Based on his kite findings, Franklin theorized that pointed rods could safely draw lightning strikes down to the ground as a way to protect buildings and structures. This led him to invent the lightning rod, which was widely adopted and saved countless structures from fires. The principles behind lightning rods are still used today to ground electrical wiring in buildings for safety.
Franklin's work with electricity also enabled him to improve early batteries for storing charge. He coined the term battery related to his experiments with capacitors connected end-to-end, which he described as giving a bigger "battery" of stored charge. His improvements to early charge storage devices would help pave the way for future battery and capacitor technologies used to store and regulate electricity.
Finally, Franklin helped popularize the idea of positive and negative electrical charge. He introduced the "single fluid" theory that differing amounts of the same electrical fluid resulted in positive or negative states, replacing early "two-fluid" theories. This discovery is the basis for why we refer to positive and negative poles and currents in electrical wiring and circuits today. The convenience of a single-fluid theory promoted much wider study into electrical science.
By pioneering a deeper understanding of electricity through his ingenious kite experiment, Franklin spearheaded innovations that formed the foundation of modern electrical systems and wiring. His findings pioneered safe methods for regulating, storing, and conducting electricity. In these ways, Franklin's simple kite truly helped to harness and revolutionize the use of electricity for the benefit of mankind.