Question #673a7

1 Answer
Jan 16, 2016

(a). Lightning conductors (term used in UK) attract lightning strikes.
(b). Lightning rods (term used in USA) with pointed ends also neutralize the positive charge of clouds through action of points.


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Lets first understand how does actually lightning strikes.

For reasons not clearly understood, there is buildup of negative charges at the bottom of the cloud. This buildup forces the negative charges of the ground to be repelled away. Thereby leaving the ground positive.
The negative charges of the cloud are repelled by the bottom of the cloud and a stream of charges is attracted to the positive ground.

Similarly, a stream of positive charges is repelled away and attracted towards the cloud. When these two streams connect, these produce conductive path for a surge of electrons to jump from the cloud towards the ground producing lightning.

(a) Lightning conductors, if placed at a high location with provide low resistance path for the lightning strikes.

(b) If pointed ends are provided at the top of lightning conductors charges can jump towards the positively charged clouds to neutralize their charge thus preventing lightning strikes.

Action of points: The charges tend to accumulate more at the sharper places than at flat areas. This results in a large charge density at sharp points. Since like charges repel, the electrons are emitted rapidly from sharper points.