Why can lightning rods protect against lightning?

In a thunderstorm, when a charged cloud layer appears over a tall building, the lightning rod and the top of the tall building are induced to a large amount of electric charge. Because the tip of the lightning rod is pointed, the tip of the conductor always accumulates the most charge during electrostatic induction.

In this way, the lightning rod accumulates most of the electric charge. The lightning rod and these charged clouds form a capacitor. Because it is sharp, the area of ​​the two plates of the capacitor is small, and the capacitance is also small, which means it can The charge contained is small, and it accumulates most of the charge. Therefore, when there are more electric charges on the cloud, the air between the lightning rod and the cloud is easily broken down and becomes a conductor. In this way, the charged clouds form a path with the lightning rod, and the lightning rod is grounded. The lightning rod can lead the electric charge on the cloud layer into the earth, so that it does not pose a danger to high-rise buildings and ensures its safety.

Mainly the principle of tip discharge. The charge distribution on a charged conductor is related to the degree of curvature of its surface. In a flat place, the electric charge is scattered and the electric field is weak; while in a sharp place, the electric charge is concentrated and the electric field is very strong. During a thunderstorm, the ground and clouds have opposite charges, and the electric field near the lightning rod is much stronger than that on the flat ground.