5.1. Definition

Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electric or magnetic field.

Electric charge is an intrinsic property of particles, such as electrons and protons. It is what allows charged objects to exert forces on each other when they are in an electric or magnetic field. This means that when an electric charge is present and interacts with another electric charge, it will either attract or repel that charge depending on the type of charge it has (positive or negative).

Think of electric charge like magnetism. Just as magnets can attract or repel each other based on their north and south poles, electric charges do the same with positive and negative charges. For instance, if you rub a balloon on your hair, electrons transfer to the balloon, giving it a negative charge. If you then bring that balloon close to a wall, it will lightly stick due to the attractive force between the negative charge of the balloon and the neutral atoms in the wall.

• Positive charge – Deficiency of electrons. • Negative charge – Excess of electrons.

Electric charges can be classified into two types: positive and negative. A positive charge occurs when an object has fewer electrons than protons, resulting in a net positive charge. Conversely, a negative charge occurs when there are more electrons than protons, creating a net negative charge. This difference in charge types is crucial because it explains the fundamental interactions between charged objects: unlike charges attract each other while like charges repel each other.

You can think of charges as having personalities: positive charges are like friendly people who attract others, while negative charges are like people who keep others at bay. For example, when you have a static charge on your body from walking on a carpet, you might feel a small shock when you touch a metal doorknob. This is the interaction between your negatively charged body and the neutral or positive charge of the doorknob.

1. Additive in nature
2. Conserved quantity
3. Quantized
4. Like charges repel, unlike charges attract

Electric charges have several important properties. First, they are additive, meaning that the total charge of a system is simply the sum of the individual charges. Second, charge is a conserved quantity, which means it cannot just appear or disappear; it can only be transferred from one object to another. Third, charge is quantized, indicating that it exists in discrete packets or units, specifically in integral multiples of the elementary charge 'e', equal to approximately 1.6 × 10⁻¹⁹ coulombs. Finally, charges exhibit a phenomenon where like charges repel each other, while unlike charges attract, a key principle that governs electric interactions.

Imagine having different colored beads representing positive and negative charges. If you have a collection of beads (charges) and you keep adding or removing them, you can count the total number of beads—you can think about the conservation of charge as ensuring that no beads mysteriously disappear while you are playing. When you place two beads of the same color close to each other, they try to roll away from each other (repel), while a positive bead and a negative bead attract each other, much like how friends might move closer together.

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