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How does a lightning conductor work?















Attaching lightning rods to prevent lightning strikes to tall buildings. This concept was originally developed by Benjamin Franklin.

What happens during a lightning strike?

Usually the air surrounding a cloud acts as a strong insulator (that is it does not conduct electric charges). However, the strong electron fields surrounding a cloud are capable of ionizing the surrounding air and make it a conductive media. This requires a high voltage as high energy is required for the ionization process and break up the usual insulation property of the air.

[During this ionization,

  1. Electrons are removed from the outer shells of gas molecules
  2.  The gas molecules are now a mixture of anions and cations
  3. The air surrounding the cloud is turned to a plasma state
  4.  Thus, electrons are free to move from the cloud towards the earth]













(Photo credit: cosmicconvergence.org) 


Benjamin Franklin suggested that a lightning rod protects a building by two methods (two proposed theories):

1. Lightning dissipation theory
2. Lightning diversion theory

Lightning dissipation theory-

According to this theory the use of a lightning rod protects the building by preventing the lightning strike. The conductive ability of a pointed object is increased due to the intense electric fields. 














(Photo credit : cnx.org)


The static charges gradually migrate towards the ground without causing large potential discharges.

(Photo credit: www.ft.com)


Lightning diversion theory-

According to this theory, the lightning conductor provides a conductive pathway of the charge to the earth. A low resistive wire is used to connect the lightning conductor to the ground. For this purpose a thick (medium diameter) copper (as copper is a strong electric conductor) wire is used.















(Photo credit: wikipedia)

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