How does a lightning rod work?

[Rosadoft]

Greetings community

An engineer came to me seeking help today. He asked me to determining the height of a lightning rod If the radius of the protection zone was given.

Assuming the roof of the building is completely flat, what would the height (h = ?) have to be for a given radius of 75 meters (r = 75m)?

 

[Drakkith]

Hmm... not sure. I did find the following with a google search: http://www.ira.usf.edu/cam/exhibitions/1998_12_McCollum/supplemental_didactics/21.Uman2.pdf

 

[Rosadoft]

Thank you! very helpful!