12) Static Electricity:

Rubbing certain insulating materials together causes negatively charged electrons to be transferred from one material to another.
This results in one material gaining a positive static charge and the other an equal negative static charge.
The direction of electron transfer depends on the specific materials involved, such as polythene and acetate rods rubbed with a cloth.

In electrostatics, only electrons move; positive charges do not move.
A positive static charge occurs when electrons are removed from a material, leaving it with a net positive charge.

As charge accumulates on an object, the potential difference between it and the earth (0 V) increases.
If the potential difference is sufficient, electrons can jump from the charged object to the earth, creating a spark.
This can also occur with nearby earthed conductors, leading to static shocks, such as when exiting a car. The car’s metal frame builds charge, and touching it allows charge to flow through you to the earth.
Sparks generally occur over small gaps, but lightning represents a much larger spark.

Charged objects exert forces on each other when brought close together.
Objects with opposite charges attract each other, while those with the same charge repel each other.
The strength of these forces diminishes with distance.
Electrostatic attraction and repulsion are non-contact forces, meaning the objects don’t need to touch to exert force.
An example is suspending a charged rod; a similar charge will repel it, while an opposite charge will attract it.