PHYSICS [5 Mark Question Answer]

Lightning is a high energy electric discharge between two adjacent clouds or a cloud or the ground. The phenomenon of lightning is caused by flow of electric charges in the atmosphere. It occurs because of a massive flow of electric charges from one cloud to another or from a cloud to the ground. When clouds move from one place to another, the friction with the surrounding air causes charges to develop on them.
The magnitude of charges increases as the clouds continue moving. Usually, the lower part of a cloud carries a negative charge, while the upper part carries a positive charge. When large clouds with negatively charged lower part pass over the electrically neutral ground, a positive charge is induced on the ground.
As air acts as an insulator, it does not allow these charges to flow. However, when the difference of charges, between two adjacent clouds or a cloud and the ground, becomes very large, the insulation of air breaks down and electrons flow through air to neutralize this charge difference. This generates a huge electric spark in the sky and is observed as lightning.

The basic property of electric charges is that two electric charges exert force on each other, that is, two similar charges repel each other and two dissimilar charges attract each other.
Experiment
Aim : To show that dissimilar charges attract towards each other.
Materials required : Glass rod, silk cloth, ebonite rod, fur cloth
Procedure : Rub the glass rod with silk cloth and ebonite rod with fur cloth. Bring the two rods close to each other. You will observe that the two rods get attracted io ards each other. This is because glass rod on rubbing with silk cloth acquires positive charge ebonite rod on rubbing with fur cloth acquires negative charge.
Aim : To show that similar charges repel each other.
Materials required : Two plastic straws and dry towel.
Procedure : Take two plastic straws and rub them on a dry towel. Place one of the straws on a wooden table. Gradually take the second straw closer to the centre of the straw placed on the table. The straw on the table rolls away. This happens because on rubbing with the towel, both straws have acquired the same charge