Distribution of charges in Action at points or Corona discharge - Lightning arrester or lightning conductor | 12th Physics : Electrostatics
Chapter: 12th Physics : Electrostatics
Lightning arrester or lightning conductor
Lightning arrester or lightning
conductor
This is a device used to
protect tall buildings from lightning strikes. It works on the principle of
action at points or corona discharge.
This device consists of
a long thick copper rod passing from top of the building to the ground. The
upper end of the rod has a sharp spike or a sharp needle as shown in Figure
1.64 (a) and (b).
The lower end of the rod
is connected to the copper plate which is buried deep into the ground. When a
negatively charged cloud is passing above the building, it induces a positive
charge on the spike. Since the induced charge density on thin sharp spike is
large, it results in a corona discharge. This positive charge ionizes the
surrounding air which in turn neutralizes the negative charge in the cloud. The
negative charge pushed to the spikes passes through the copper rod and is
safely diverted to the Earth. The lightning arrester does not stop the
lightning; rather it diverts the lightning to the ground safely.
Related Topics