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Video: The Development Of The Lightning Rod
2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-05-24 11:12
Technically speaking, a lightning rod is nothing more than a metal rod attached to a building to protect the structure from lightning. When lightning strikes, it is preferred to strike a raised rod and conduct it through a wire to earth rather than going through the building, for example, where it could start a fire or cause an electric shock
One of the founding fathers of the later United States of America is considered the inventor of the lightning rod: Benjamin Franklin. He was also a writer, printer, political philosopher, politician, Freemason, postmaster, scientist, inventor, humorist, civil activist, statesman and diplomat. As a scientist, he was an important figure in American education and the history of physics due to his theories and discoveries about electricity. In addition to the lightning rod, Franklin invented bifocal glasses and the Franklin oven named after him.
Beginnings of lightning research
Benjamin Franklin was interested in everything related to electricity in the 1740s. According to his theory, expressed in 1749, that lightning is nothing more than electrical sparks, i.e. a form of arc on a huge scale, he proposed an experiment in June 1752 that was similar in structure to a lightning rod: during a thunderstorm, a kite should rise on a metal wire and to be hit by lightning, the metal wire was to transfer the charge to the ground, where it could be stored with an early type of capacitor, for example, and subsequently detected on the capacitor.
Fortunately, the dragon was not struck by lightning, because Franklin, who controlled the dragon, would not have survived. However, the experimental set-up was able to demonstrate static electricity in the air and thus also that lightning is an electrical charge. In a similar experiment, self-styled lightning researcher Georg Wilhelm Richmann became sadly famous as the first person in history to be electrocuted.
How much energy a lightning has
Lightning bolts that discharge from the cloud into the earth's surface can be classified into positive and negative according to the direction of the current flow. Most of these flashes are negative, i.e. the negative charge goes to earth, the electrons travel down the lightning channel. With positive flashes, the process is reversed - the positive charge is transferred to the bottom. Only about 5% of all flashes are positive.
Positive lightning strikes are usually much more intense than their negative counterparts. An average negative lightning carries an electrical current of 30,000 amperes (30 kA) and transfers 15 coulombs of electrical charge and 1 gigajoule of energy. Large negative flashes can transmit up to 120 kA and 350 C. The average positive earth lightning has approximately twice the peak current of a typical negative lightning and can generate peak currents of up to 400 kA and charges of several hundred coulombs.
Lightning rods prevail
A lightning rod later installed by Franklin protected his home from disaster while he was away. Franklin proudly wrote: "After all, this is how the invention was useful for the inventor." With the associated popularity and above all the proven protective effect, "magic" lightning rods on churches - such as the four deer antlers on St. Stephen's Cathedral in Vienna - could be dismantled and be replaced by correct ones. However, according to the Austrian satirist Karl Kraus, this measure led to mistrust of God.
During Benjamin Franklin's stay in Paris from 1776 to 1785, enthusiasm for Franklin's invention led to lightning rods in French fashion in the better-off circles of the Parisian population, the protective function of which, however, was never proven. Lightning protection hats and umbrellas were therefore not visible for long.