Transverse & longitudinal waves
Electric charge is the basic property of matter. This electric charge is carried by some elementary particles like electrons and protons.
When these particles are
placed close to each other they will experience a force.
This force may be attractive or repulsive.
Types of electric charges
There are two types of electric charges namely positive and negative. Electrons are called negatively charged particles and protons are called positively charged particles.
If two charged particles of similar charge are placed close to each other, they get repelled because the force present between them is repulsive. On the other hand, if two charged particles of opposite charge are placed close to each other, they get attracted because the force present between them is attractive. We can also simply define it as opposite charges attract and like charges repel.
An object said to be negatively charged if it has excess number of electrons than protons. On the other hand, if the object has excess number of protons than electrons then the object is said to be positively charged. When the number of electrons and protons are equal then the object is said to be neutral.
The SI unit of electric charge is coulomb (C). The coulomb is defined as the quantity of charge that is passed through the electrical conductor carrying one ampere in one second. The symbol Q is used to denote the charge.
Electro-meter is used to measure the quantity of electric charge. It can also measured indirectly by using ballistic galvanometer.
Around 600 BC, ancient Greek philosopher "Thales of Miletus" proposed that charge or electricity could be gathered by rubbing fur (hair of non-human animals) on substances like amber.