We all have experienced electric charge in our daily life knowingly or unknowingly. The example of electric discharge during thunderstorm lightning is one of the common phenomena we can see in our sky.
Sometimes we also experience electric shock from touching the iron bars of any moving object, like a car or bus. When an amber rubbed with a cloth then it generates an electric charge and this charge can attract light objects like a little piece of straw or paper. The electricity is taken from the Greek word Elekton that means Amber.
Not only amber but also many pairs of known material can also generate an electric charge after rubbing it and these charges can attract light objects.
Types of electric charge
A basic practice at home we can go for that when we do comb with our hairs, the teeth of the comb get rubbed between hairs and generate electric charges. If we took the comb to near to a small piece of paper it will attract the paper.
Similarly, if we rub two glass rods with a silk cloth and take them near to each other, they will repel each other.
For many years scientists did experiments and analyzed that these electric charges are two types.
They found and concluded that unlike electric charges attract each other, for example, when amber rubbed with a silk cloth. Whereas like charges repel each other, for example, charges between two glass rods.
There are two types of electrical charges and they have a property to repels and attract if brings relatively near to each other. So, American scientist Benjamin Franklin suggested two names for these types of charges, 1. Positive charges, 2. Negative charges.
Two same charges repel (+ve and +ve, -ve and -ve), whereas two different charges attract (+ve and -ve, -ve or +ve). If any object has no charge, it is called that object is electrically neutral.
Most of the elementary particles have the property of charge. They preserve some positive or negative charges. As elementary particles create sub-atomic particles and other material in the universe. So basically we can say that every matter in the universe can have the property of electric charge.
An electron has a negative charge and a proton has a positive charge, whereas a neutron has no charges. If a matter has more protons than the number of electrons then it will have a positive charge and the matter is called positively charged matter. But if a matter has more electrons than protons then it will have a negative charge and the matter is known as negatively charged matter. Whereas if the matter has the same number of protons and electrons then the matter will be neutral.
Elementary charge is the magnitude of charge carried by a single proton or electron. It is denoted by ‘e’ or ‘qe’ and has a fundamental constant value of 1.602176634 × 10−19 C. This mathematical charge is the smallest charge that can exist freely.
The charge of any matter would always be an integer value of the elementary charge. That means it could be 0, 1e, 2e, -e, -5e, etc. But it could not be 1/2e, 1.8e, etc. Though a fundamental particle quark has a charge of 1/3e, they exist only in the group (not freely) and made protons.
The proton has a value of +e and the electron has a value of -e. The only ‘e’ is sometimes called positive elementary charge. In the International System of Units (SI) the unit of electric charge is ‘Coulomb’. The approximate value of an elementary charge is ‘1.6 × 10-19 C’ where C is denoted one coulomb.
Mathematically, e = 1.6 × 10-19 C.
⇒ C = 6.24 × 1018 e.
Thus, one coulomb = 6.24 × 1018 elementary charges.
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