Electric Charge

Introduction

The electric and magnetic field has effects on any material that is evaluated in terms of electric charge. The electric charge is thus a physical property of the matter due to some of its constituents and their behaviour in the respective electric and magnetic fields. It constitutes the electrons’ charge, the charge on protons, and the overall charge on the matter.

It can be either positive or negative, depending on the types of materials. Hence, neither positive and negative charges can be created nor destroyed. This is the basis of electric charge, and there are different properties and associated methods of charging.

Definition of electric charge:

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 a magnetic and 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 quantized 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.

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 charge of the electron 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.

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. It is also called electrification by friction and requires close contact between the two different objects. It is impossible to charge two products through conflict if they’re not close to each other.
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. Hence, the contact between a charged and the uncharged material may get formed in conduction.
3. Charging through induction: In this process, the charge transfer occurs when two different objects are distantly located. Hence, in this process, there is no close contact between the two things.  It is different from the conduction on the same note of zero contact between two objects. The electron’s charge in induction is obtained due to a change in its magnetic field only. Hence, an electron carries a dash charge induced in the opposite direction to that of the magnetic field. Therefore, the charge obtained through induction remains constant.

How to measure electric charge?

Coulomb is the SI unit of electric charge that is the quantity of charge transferred in one second. Hence, electric charge is calculated as:

Q=I×t

Here,

Q is the electric charge

I is the electric current

t is the time

Main properties of electric charge:

The main properties of electric charge include:

1. Additivity property: It can be added by simple algebra rules
2. Conservation property: Charges can never be created nor be destroyed as they can only be transferred from one to another using different methods.
3. Quantization property: The electric charge of a body is quantized. Hence, it is not a continuous quantity and is the integral multiple of one electron charge. The electron can’t get divided further, and hence the charge is always an integral multiple of 1.6*10-12.
4. Like charges repel each other while unlike charges attract each other.

What is Coulomb’s Law?

Coulomb’s Law defines the strength of the force between two charges that may be attracting or repelling each other. Hence, it states that the electrostatic force of attraction or repulsion between two point charges varies directly to the product of the magnitudes of these two point charges and is further inversely proportional to the square of the distance between these two.

The expression represents it:

F= kq1q2/ r2 

Here,

F is the electrostatic force

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

q1 and q2 are point electric charges

r is the distance between the two point charges.

Conclusion

The electric charge is quantized with one of the observed properties due to its behaviour in electric and magnetic fields. 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,” and Coulomb’s law defines it. Coulomb is the SI unit, and other units include Ampere-Hour, Faraday, etc. It has predefined properties and is a scalar quantity despite having both magnitude and direction.