Some Misuse of Static Electricity:
Hanging metal chain with petrol transporting truck: A metal chain has to be hung touching the road with the trucks that carries petrol, diesel or other liquid fuels. When a truck moves along the road, the petrol in the tank dashes against the inner surface of the tank and oscillates to and fro. As a result of this, the friction charge is stored in petrol. If any spark takes place from the edge of the tank it may cause a serious accident and may set fire. So the charges in petrol are not safe Therefore a chain is connected at the back of the tank so that the charge can pass through it to the ground easily as metal is a good conductor.
No direct connection between metal pillar and electric line: The metal pillars on the road have no direct connection with electric lines pulled over the pillars. As metals are good conductors, the electricity of the wire may pass through the pillar to the ground if the pillar has a connection with wires. If anyone touches the pillar he could immediately be electrified causing serious accident. So the wires are connected to the pillars by a porcelain cup.
Thunder bolt and lightning conductors: We know that there is water vapor in atmosphere. This water vapor is condensed on the charged ions in the atmosphere and form water droplets and become charged with electricity. When these water droplets gather together cloud is fonned. Cloud can be charged either positively or negatively. When two oppositely charged clouds come close to each other then electrical discharge takes place between them and makes huge spark. This is called lightning or electric flash.
During electric flash the air around the cloud expands suddenly by getting heated. Due to sudden expansion the pressure of the air lowers much. Then neighboring air at higher pressure contracts the expanded air. Due to this sudden expansion and contraction of air, violent sound is produced. This is known as the roaring of thunder. If there is too much charge on a cloud then it includes opposite charge on the surface of the earth and electric discharge takes place. This is known as thunder bolt.