2.1. Electric Charge

Electric charge is a fundamental property of matter. There are two types of electric charges: positive and negative.

Electric charge is an intrinsic property of elementary particles, which gives rise to electrical phenomena. Matter can possess one of two types of electric charges: positive or negative. This property determines how particles interact with each other. When two charges of the same type come close, they repel each other, while charges of opposite types attract each other.

Imagine two magnets. When you try to push the north poles of two magnets together, they push away from each other. This is similar to how like charges (positive or positive, negative or negative) repel each other. However, if you bring a north pole close to a south pole, they attract, just like opposite charges do.

• Protons carry a positive charge.
• Electrons carry a negative charge.
• Neutrons carry no charge.

In an atom, protons are positively charged particles found in the nucleus. Electrons, which orbit around the nucleus, carry a negative charge. Neutrons are also located in the nucleus but have no charge at all, making them neutral. The balance between protons and electrons in an atom determines the overall charge of that atom: if there are more protons than electrons, the atom is positively charged, and vice versa.

Think of an atom like a tiny solar system. The protons are like the sun (positive), electrons are like the planets (negative) moving around it, and neutrons are like asteroids (neutral). The balance of planets (electrons) around the sun (protons) determines how the whole system behaves.

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

The coulomb is the standard unit used to measure electric charge in the International System of Units (SI). One coulomb represents a large number of charge; it is defined based on the amount of charge that flows through a conductor in one second when there is a current of one ampere. Understanding coulombs helps in quantifying charge in various electrical applications.

If you think of electric charge like water flowing through a hose, then the coulomb is akin to measuring the liters of water that flow through the hose in a certain amount of time. Just as you can have more water flowing through (more liters) with higher pressure, you can also have more charge flowing in a circuit (more coulombs) with a higher current.

Like charges repel each other, while opposite charges attract.

This principle is fundamental to understanding electric charge interactions. When two similar charges (either two positives or two negatives) are brought near each other, they experience a force that pushes them apart—this is called repulsion. Conversely, when a positive charge and a negative charge are brought close, they attract each other, pulling together. This behavior is essential in the formation of atoms and molecules, as it leads to the bonding of different elements.

Consider static electricity: when you rub a balloon on your hair, both the balloon and your hair gain electric charges. The hair becomes positively charged and tries to stand up away from your head because like charges repel each other. When you bring the charged balloon near, your hair is attracted to it, like how positive and negative charges interact.

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