# Charge

Electric charge is a fundamental property of matter that governs its interaction with electric and magnetic fields.

• Electric charge carriers, protons (+) and electrons (-) are the primary charge carriers in matter.
• There are two types of electric charge:
• Positive charge: Carried by protons, found in the nucleus of atoms.
• Negative charge: Carried by electrons, which exist in orbitals around the nucleus.
• Neutons, the other particles within the nucleus of an atom, have no charge.
##### Properties of electric charge
• Like charges repel, opposite charges attract: Particles and objects with the same type of charge repel each other, while objects with opposite charges attract each other.
• Electrostatic force: The force between charged objects is called the electrostatic force, and it’s governed by Coulomb’s law.
• Conservation of charge: The total electric charge in an isolated system is always conserved. It cannot be created or destroyed, only transferred between particles or regions.
• This means, for example, that even though electrons can move between energy levels within an atom, the total number of protons (positive charges) and electrons (negative charges) remains constant, upholding the principle of conservation of charge.
##### Examples of charge
• Static electricity: Rubbing a balloon on your hair transfers electrons, creating a static charge that can make hair stand on end or attract small objects.
• Electric current: The flow of electrons through a conductor, like a wire, creates an electric current, which can be used to power our devices.
• Lightning: Lightening is a dramatic example of charge-discharge in nature, caused by the buildup of static electricity in clouds.
###### About electric charge and energy in an atom
• An atom has a set number of particles that determines what kind of element they are.
• Each element has a specific number of protons (positive charge) in its nucleus. It is this number that defines an element and cannot change in everyday situations.
• Protons in the nucleus of an atom are very stable and don’t typically move around or get created or destroyed. There are a fixed number and they maintain their positive charge within the atom.
• Electrons (negative charge) surround the nucleus, with the number typically matching the number of protons to create a neutral atom.
• Regardless of their energy level, an atom retains the same number of electrons it started with.
• If an atom loses or gains an electron, it is no longer considered the same element and becomes an ion.
• The movement of electrons within an atom doesn’t change their total charge because the number of protons and electrons remains constant. However, the movement of electrons does affect the amount of energy within the atom.
• Electrons in an atom change energy levels as they gain and lose energy.
• So when an electron absorbs energy (such as visible light), it jumps to a higher energy level further away from the nucleus. However, the electron itself remains negatively charged, it just occupies a different position within the atom.
###### References
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• Electric charge is a fundamental property of matter that governs its interaction with electric and magnetic fields.
• Electric charge carriers, protons (+) and electrons (-) are the primary charge carriers in matter.
• There are two types of electric charge:
• Positive charge: Carried by protons, found in the nucleus of atoms.
• Negative charge: Carried by electrons, which exist in orbitals around the nucleus.
• The smallest unit of charge is the elementary charge (e ≈ 1.602176634 × 10^-19 C), carried by each individual proton and electron.