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Electric Charge

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Electric Charge is the basic property of the material that is responsible for the electrostatic property of the material. It is the amount of electric energy that is used for various purposes. Electric charges are categorized into two types that are,

  • Positive Charge
  • Negative Charge

Positive and Negative charges have opposite properties. We have to study Electric Charge in Class 10 and Class 12. In this article, we will learn about electric charge, types of electric charge, methods of charging, and others in detail.

What is Electric Charge?

Electric Charge is the fundamental property of the atoms. Atoms are made up of subatomic particles called: electrons, protons, and neutrons. These particles are charged particles.

  • Protons have a positive charge.
  • Electrons have a negative charge.
  • Neutrons are neutral in nature.
  • If an object has a balanced proportion of positive and negative charges, it is said to be electrically neutral.
  • If there is an excess of either electrons or protons in an object, then it is considered a charged object.

On the basis of polarity electric charges are categorized as either Positive Charges(Protons) or Negative Charges(Electrons). Charges can be found in all types of bodies.

Electric Charge Physics Definition

In physics electric charge is defined as the property of the material that is responsible for electromagnetic properties of the materials. It is denoted using symbol Q and is measured in Coulomb. Other units to measure electric charge are Faraday, Ampere-Hour.

History of Electric Charge

The word Electricity has come from the word electron which came from a Greek word named “Elektron” which means Amber in Greek. In 1600, William Gilbert, a philosopher mentioned “Amber Effect” in his book which explained how the mineral Amber which is used to make jewellery keeps on getting small fibres of cloth attached to it making it difficult to wear as an ornament.

Later in the 18th century, Benjamin Franklin conducted experiments and deduced that there exist charges, and named charges as positive and negative. The concept of charges completely came into the picture after batteries were introduced.

Is Electric Charge a Vector Quantity?

No, Electric charge is a scalar quantity, it has magnitude but no fixed direction. Scalar quantities are those which only have magnitude and no direction. Electric Charge does not follow the Triangle law of Vector Addition.

Electric Charge can be directly added as an algebraic sum of two quantities. If a current i1 and i2 flow through the wire and meet at the junction then their resultant is calculated as (i1 + i2)

Measuring Electric Charge

Electric Charge is measured in ‘coulomb’, which is the SI unit for measuring electric charge.

If 1 Ampere current flows through a wire then, “One coulomb is defined as the charge that passes through the cross-section of the wire in one second.” i.e.

Q = I.t

where,

  • Q is the electric charge
  • I is the electric current
  • t is the time

Electric Charge Formula

The formula to calculate the charge passing through the conductor is,

Q = ne

where,

  • Q is the charge passing through conductor
  • n is the number of electrons
  • e is charge on 1 electron 

Note: The charge on one electron is 1.6 × 10-19 C

SI Unit of Electric Charge

SI unit of Electric Charge is Coloumb and it is represented by the symbol C. One Coloumb charge is defined as the electric current of one Ampere passing through the conductor in one second.

Dimensional Formula of Electric Charge

The electric charge is measured by multiplying current with time. Thus, the dimensional formula of electric charge is, [I1T1].

Elementary Electric Charge

The elementary electric charge is Electron and is denoted by the symbol “e”. It is a fundamental constant and its value is e = 1.602 × 10-19 coulomb.

Electric Charge of Proton

Proton is considered to be the positive electric charge it is denoted by symbol, ‘p’ and its value is, p = 1.602 × 10-19 C.

Electric Charge of Electron

Electron is considered to be the negative electric charge it is denoted by symbol, ‘e’ and its value is, e = -1.602 × 10-19 C.

Types of Electric Charges

Electric Charges are divided into two categories:

  • Positive(+) Charge
  • Negative(-) Charge

Positive Charge: If an atom has more protons than electrons then it is called to have a positive charge.

Negative Charge: If an atom has more electrons than protons then it is called to have a negative charge.

Neutron has no charge. When there is an equal number of protons and electrons then we say the atom is neutral. 

Methods of Charging

Electric charge is a basic property of anybody, it can be transferred from one body to other. Gaining or Lossing electric Charge is called Charging.

Charging can be achieved in the three following ways:

  • Charging by Friction
  • Charging by Conduction
  • Charging by Induction

Charging by Friction

When two things are rubbed together, electrons are transferred between them, and they become charged. Also, when a rubber balloon is rubbed with animal fur, such that the rubber balloon attracts the electrons from the animal fur. As a consequence, rubber has an abundance of electrons whereas fur has a scarcity of electrons. These are known as charged objects

Charging by Conduction

The method of charging an uncharged object by bringing it close to a charged object is known as charging by conduction. The charged conductor has an unequal number of protons and electrons; hence when an uncharged conductor is brought near it, it discharges electrons to stabilize itself.

The image given below shows Charging by Conduction.

Charging by Conduction

Charging by Induction

The process of charging an uncharged conductor by bringing it near a charged conductor without any physical contact is known as charging by induction.

Basic Properties of Electric Charge

A charge is the fundamental property of an atom. It has various properties, some of the basic properties of electric charge are

  • Force between two Charges
  • Charges are additive in nature
  • Quantization of Charge
  • Conservation of Electric Charge

Force between two Charges

There is a force between two charges and its value is determined using Coloumb’s law. The basic property of the charge is that

  • Like Charges repel each other.
  • Unlike Chages attract each other.

The following image shows the nature of the force between two charges.

Force between two Charges

Charges are Additive in Nature

Electric charge behaves as a scaler quantity and can be directly added to obtain a higher charge. For example, if we have three charges q1, q2 and q3 arranged in the system then the total charge of the system is given by finding the algebraic sum of q1, q2 and q3.

Let’s take a system of n charges q1, q2, q3, q4 ………. qn, then the net charge of the entire system (say Q) is calculated as,

Q = q1 + q2 + q3 + q4 + ……. + qn

Additive Nature of Nature

Quantization of Charge

Quantization of the charge is the fundamental concept of physics it signifies that a charge can neither be created nor be destroyed and can only be transferred from one body to another. 

Also, the charge can exist as an integral multiple of the fundamental charge i.e. Q = ne which means charge of 2e, 4e, 98e and others exist but charges in the form of 1/2e, 3/4e does not exist.

Learn more about, Basic Properties of Electric Charge

Conservation of Electric Charge

Conservation of Electric charge states that, “the total electric charge in an isolated system is always constant.” We can also states that, the net quantity of the electric charge (positive charge – negative charge) is always conserved.

Electric Charge Field

The electric field due to electron (negative electric charge) is towards the charge and the electric field due to proton (positive electric charge) is away from the charge. The image showing the electric field of both the charges is added below,

electric-charge-field

Coulomb’s Law

Electric charges have specific properties that say like charges repel each other whereas unlike charges attract each other. The magnitude of the force between the charges can be understood using Coulomb’s Law.

Coulomb’s Law says that,

“The magnitude of the electrostatic force between two point charges (either attraction or repulsion) is directly proportional to the product of the magnitudes of charges and is inversely proportional to the square of the distance between them.”

Coulomb’s Law is mathematically explained as,

F = kq1q2 / r2

where,

  • k is Coulomb’s constant and its value is, 8.988×109 N⋅m2/C2
  • r is distance between the charges
Coulomb’s Law

Read More,

FAQs on Electric Charge

1. What is Electric Charge Class 10?

Electric Charge is the fundamental property of the atom which is responsible for electromagnetic attractions. The charges are of two types,

  • Positive charges (Protons and Holes)
  • Negative Charges (Electron)

2. How Electric Charge is Produced?

Charges can neither be created nor be destroyed they can only be transferred from one body to another in the form of electrons. If a body looses an electron it acquires a positive charge whereas if a body gains an electron it acquire a negative charge.

3. What are Types of Charges?

Positive and Negative are the two types of charges. Charges that are similar repel each other, whereas charges that are dissimilar attract each other.

4. What is Static Charge?

The electric charges generated by rubbing are called static charges. The static charges do not move while charges move in electric current.

5. What is the Unit of Electric Charge?

Electric Charge is measured in Coulomb. It is a bigger unit of charge so it is measured in smaller units called microcoulomb.

6. Define One Coulomb.

If one Ampere current passes through a steady conductor in one second then we say the charge in the conductor is one coulomb and is equivalent to 6.415×1018  electrons



Last Updated : 18 Oct, 2023
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