Pointed Lightning Rods
Name: A. B.
Why does the lightning conductor have pointed shape? I
know it has something to do with electric field lines. Please explain.
The electric field in a conductor is very strong at a sharp edge or point
so it provides a good target for a lightning discharge. You can find the
quantitative details in a text on electricity and magnetism. Richard Fey
also gives a good treatment in Vol. 2 Chapter 9 of "Lectures on Physics". In
addition, check out the website:
It has a lot of good information.
Electrons tend to move to and from pointed objects. They tend to remain on
smooth round surfaces (like the globes on a Van de Graf generator). We do
not want a charge to build up between buildings and clouds until a sudden
discharge can do great damage. Instead, by applying a pointed lightning rod
the charge is dissipated slowly keeping the electrical potential difference
low. Unlike the Hollywood version, lightning seldom strikes a lightning
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Update: June 2012