Assertion: The lightening conductor at the top of high building has sharp pointed ends.
Reason: The surface density of charge at sharp points is very high resulting in setting up of electric wind.

Options

A. Both assertion and reason are true and the reason is the correct explanation of the assertion
B. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
C. Assertion is true but reaso is false
D. Both assertion and reason are false

Answer

A

Explanation

We know that surface density of charge is very large on the sharp ends of a conductor. This charge from pointed ends sets up a charged electric wind. This charged electric wind comes in contact with the charged clouds and then source of its charge is neutralized and so potential drops between building and clouds. Hence, chancws of lighting on building is reduced. Even if lightining strikes the building, charge is conducted by the lightining conductor to the earth the there is no harm to building.