Electric charges

The electric charge is defined as the property of the matter that is due to its subatomic particles. It causes the material to experience a force when placed in an electric field. The electric charge is a scalar quantity. It has both magnitude and direction but is an exception to the general vector quantities. If it has been a vector quantity, the two charges meeting at one point will result in the vector sum of the total charges. But it is not the same as the sum of the combined charges due to two different charges connecting at one point to the algebraic sum of both. Hence, despite having magnitude and direction, electric charge is quantised as a scalar quantity only.

Its symbol is “Q.” The SI unit of electric charge is Coulomb, and other units include Faraday, Ampere-Hour, etc.

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Types of electric charge:

There are only two types of electric charge:

Positive charge and negative charge

The positive charge is denoted by (+) and is the charge on the protons in the atom. If a material has a positive charge, the number of protons is higher than the number of electrons.

The negative charge is denoted by (-) and is the electron’s charge in the atom. If a material has a negative charge, the number of electrons is higher than the number of protons.

When there is a balance between the number of protons and the number of electrons in the material, the total charge is neutral.

Basic Properties of Electric Charge

The electric charges are called point charges when the dimension of the electrically charged bodies is minimal. Let’s take a note of the basic properties of electric charge. 

1. Additive property of electric charge: Electric charges are cumulative, and the type of electric charge they carry influences this property. It has a scalar value. It is possible to add the charges directly. 
2. Conservative Nature of Electric Charge: A particle’s electric charge is conservative. It signifies that the charge can’t be created or eliminated in any way. Conduction and induction are two mechanisms that can transfer charges from one system to another. 
3. Quantisation of Charge: This is one of the fundamental properties of electric charge. The charge is technically a quantised quantity. The integral multiples of the basic unit of charge (i.e. 1.6 x 10-19 C) can be used to indicate a system’s net charge. If the body’s net charge is q, the equation can be stated as:

q = ne

n can be any integer.

Methods of charging:

There are three different ways to charge any material. These are:

1. Charging through friction: In this process, the charge transfer occurs when two different objects are rubbed together. It is possible as one object gains electrons while the other object loses electrons. The object losing electrons becomes positively charged while the one achieving electrons gains some charge, i.e., negative charge. 
2. Charging through conduction: In this process, the charge transfer takes place by bringing the uncharged material close to the charged material. The electron’s charge is passed as the charged material loses its charge carriers to the uncharged material when both are nearby. 
3. Charging through induction: In this process, the charge transfer occurs when two different objects are distantly located. Hence, there is no close contact between the two things in this process.

How to measure electric charge?

Coulomb is the SI unit of electric charge.

 The quantity of charge transferred in one second is called current. Hence, electric charge is calculated as:

Q=I×t

Here,

Q is the electric charge

I am the electric current

t is the time

Coulomb’s Law

Coulomb’s law defines the strength of the force between two charges that may be attracting or repelling each other. Hence, According to Coulomb’s law,  the electrostatic force between two different objects is dependent on the charge of the bodies. There are also few charged bodies in any substance known as neutrons. Moreover, these bodies are neutral and do not help in generating electrostatic force. 

The expression for Coulomb’s force is:

F= kq1q2/ r2 

Here,

F is the electrostatic force

K is the Coulomb’s constant and is equal to 8.988*109 Nm2/C2

K = 14𝛑𝞊

q1 and q2 are point electric charges

r is the distance between the two point charges.

Conclusion

The electron’s charge is negative while that on the proton is positive. However, the overall charge on any material depends on the majority of the charge carriers only.

It is easy to charge the materials using friction, conduction, or induction. The symbol of electric charge is “Q,” Coulomb is the SI unit. Despite having both magnitude and direction, it has predefined properties and is a scalar quantity.