1) Definition

Charge is a fundamental property of matter that allows it to produce or experience electric and Magnetic Field. It is quantified by a specific value, and the smallest possible charge observed in nature belongs to elementary particles such as electrons and protons.

The charge of an electron or proton is:

$$1 \, e = 1.6 \times 10^{-19} \, \mathrm{C}$$

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2) Types of Charges

There are two types of charges based on their nature:

• Positive Charge: Found in protons.
• Negative Charge: Found in electrons.

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3) Interaction of Charges

• Like charges (e.g., positive-positive or negative-negative) repel each other.
• Unlike charges (e.g., positive-negative) attract each other.

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4) Unit of Charge

The SI unit of charge is the coulomb (C).

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5) Properties of Charge

i) Quantization of Charge

Charge exists only in discrete packets and cannot take fractional values. The charge on any object is an integer multiple of the elementary charge:

$$q = n \cdot e$$

Where $n = 1, 2, 3, \dots$. Examples of non-allowed charges include $0.5e$, $1.5e$, etc.

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ii) Charge is a Scalar Quantity

• Charge does not have a direction, only magnitude.
• It can be added or subtracted using simple algebraic rules.

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iii) Charge is Transferable

• Charges can move from one object to another.
• For instance, when an uncharged body contacts a charged body, the uncharged body acquires charge.

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iv) Charge is Always Associated with Mass

Charge cannot exist independently without being associated with some form of mass. All charged particles have mass.

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v) Conservation of Charge

Charge can neither be created nor destroyed. In any closed system, the total charge remains constant. This principle applies universally.

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Summary

Key Points:

Concept	Explanation
Charge	Property of matter that allows interaction with electric and magnetic fields.
Types	Positive (protons) and Negative (electrons).
Quantization	Charge exists in integer multiples of $e$.
Conservation	Total charge in a system is constant.

Significance:

Charge plays a crucial role in the study of electromagnetism and is essential to understanding phenomena like electricity, magnetism, and the forces that govern atomic and molecular structures. This concept underpins technologies like electric circuits, semiconductors, and communication systems.