Education in India

Lightning Rod



Invented by : Benjamin Franklin
Invented in year : 1752

A lightning rod or lightning conductor is a metal rod or conductor mounted on top of a building and electrically connected to the ground through a wire, to protect the building in the event of lightning. Whenever lightning strikes the building it strikes the rod and is conducted to ground through the wire, instead of passing through the building, where it could start a fire or cause electrocution. A lightning rod is a single component in a lightning protection system. A lightning rod is a pointed metal rod attached to the roof of a building. The rod might be an inch (2 cm) in diameter. It connects to a huge piece of copper or aluminium wire that's also an inch or so in diameter. The wire is connected to a conductive grid buried in the ground nearby. The purpose of lightning rods is often misunderstood. Many people believe that lightning rods attract lightning but it is a safety measure in case of lightening. Relevance of lightning rods is not only when a strike occurs or immediately after a strike occurs as regardless of whether or not a lightning-rod is present, the strike will still occur.

History

Lightening rods have been in existence in ancient times, as is evident in Sri Lanka's, Kingdom of Anuradhapura ( 205 km. north of Colombo) that dates back to thousands of years. The Sinhalese kings who mastered construction of stupas and advanced building structures, installed a metal tip made of copper on the highest point of every building to conduct any lightning charge. Lightning conductors may have been used in Nevyansk tower, where the roof of the tower is crowned with a metallic rod in the shape of a gilded sphere with spikes. However, the true purpose and intent behind the metal rooftop remains unknown. As, there is no record of who invented these lightning rod, the credit is given to Benjamin Franklin who conducted experiments in this field.

During 1746, Franklin, an american scientist and inventor, first stumbled upon other scientists' electrical experiments in Boston, Massachusetts. He became interested in finding more about electricity. In 1749, Benjamin Franklin invented the lightening rod. They were also known as 'Lightning Attractor' or 'Franklin Rod'. His invention was a result of his investigations of electricity. By 1750, in addition to wanting to prove that lightning was electricity, Franklin began to think about protecting people, buildings, and other structures from lightning. At that time he had observed that a sharp iron needle would conduct electricity away from a charged metal sphere. He first theorized that lightning might be preventable by using an elevated iron rod connected to earth to empty static from a cloud. This grew into his idea for the lightning rod. Franklin described an iron rod about 8 or 10 feet long that was sharpened to a point at the end. In June of 1752, Franklin was in Philadelphia, waiting for the steeple (the steeple would act as the lightning rod) on top of Christ Church to be completed for his experiment. He grew impatient, and decided that a kite would be able to get close to the storm clouds just as well. Ben needed to figure out what he would use to attract an electrical charge; he decided on a metal key, and attached it to the kite. Then he tied the kite string to an insulating silk ribbon for the knuckles of his hand. At the first sign of the key receiving an electrical charge from the air, Franklin knew that lightning was a form of electricity. Franklin began to advocate lightning rods that had sharp points as they conducted electricity better as compared to blunt one's. Václav Prokop Diviš, czech priest, theologian and natural scientist also invented a lightning rod independently of Benjamin Franklin's invention between 1750 and 1754.

Development of the invention of lightning rod

The first lightning conductors on ships were supposed to be hoisted when lightning was anticipated, and had a low success rate. In 1820 William Snow Harris invented a successful system for fitting lightning protection to the wooden sailing ships of the day, but despite successful trials which began in 1830, the British Royal Navy did not adopt the system until 1842, by which time the Imperial Russian Navy had already adopted the system.

Nikola Tesla's U.S. Patent 1,266,175 was an improvement in lightning protectors. The patent was granted due to a fault in Franklin's original theory of operation; the pointed lightning rod actually ionizes the air around itself, rendering the air conductive, which in turn raises the probability of a strike.

In the 1990s, the 'lightning points' were replaced as originally constructed when the statue of Freedom atop the United States Capitol building in Washington, D.C. was restored. The statue was designed with multiple devices that are tipped with platinum. The Washington Monument also was equipped with multiple lightning points and the Statue of Liberty in New York Harbor gets hit with lightning which is grounded out.

A lightning protection system was developed to protect buildings. It typically includes a rooftop network of conductors, multiple conductive paths from the roof to the ground, bonding connections to metallic objects within the structure and a grounding network. The rooftop lightning rod is a metal strip or rod, usually of copper or aluminium. Lightning protection systems are installed on structures, trees, monuments, bridges or water vessels to protect from lightning damage. Individual lightning rods are sometimes called finials, air terminals or strike termination devices. These rods can be placed at regular intervals on the highest portions of a structure.

Lightning protection for aircraft is provided by mounting devices on the aircraft structure. The protectors are provided with extensions through the structure of the aircraft's outer surface and within a static discharger

A lightning protection installation on a watercraft comprises a lightning protector mounted on the top of the mast or superstructure and a grounding conductor in contact with the water. Electrical conductors attach to the protector and run downward to the conductor. For a vessel with a conducting (iron or steel) hull, the grounding conductor is the hull. For a vessel with a non-conducting hull, the grounding conductor may be retractable, part of the hull, or attached to a centreboard.

Role of the invention of lightning rod in the improvement of human life

  • Franklin's lightning rods were started being used to protect many buildings and homes.
  • Lightning rods helped in a better understanding of lightening and electricity.
  • The invention paved way for improved and other forms of lightening protection system.
Other Inventions
  Page updated on : 22-Dec-2009  | Total page views : 1561


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