how does the lightning rod work..?

Answer 1

A lightning rod (or lightning protector) is a metal strip or rod, usually of copper or similar conductive material, used as part of lightning safety to protect tall or isolated structures (such as the roof of a building or the mast of a vessel) from lightning damage.

A lightning rod is connected via a low-resistance wire or cable to the earth or water below, where the charge may be safely dissipated. Lightning rods sometimes possess a short circuit to the ground that is interrupted by a thin non-conductor over which lightning jumps. Ideally, the underground part of the assembly should reside in a muddy area, or an area that tends to become so during storms. If the underground cable will resist corrosion well, it may be covered in salt to improve its electrical connection with the ground.

Electricity travels along the path of least resistance, so an object outside the critical distance is unlikely to be struck by the leader if there is a grounded object within the critical distance. Noting this, locations that are safe from lightning can be determined by imagining a leader's potential paths as a sphere that travels from the cloud to the ground.

Answer 2

Lightning is caused by a build up of opposite (positive and negative) electrical charges. When the charges get strong enough, there is lightning flashing to equalize the charges again.

If the opposing charges are in the earth and the clouds (as opposed to cloud to cloud) the lightning flashes between clouds and earth when the charges build up enough.

Lightning rods stop this from happening by dispersing the charge in the earth slowly into the sky, thus keeping the opposing forces from reaching the flash point. The opposite end of the lightning rod you see on a building is an attached wire running to and buried deeply into the ground.