Introduction to Electricity

Defintion

• Electricity is an electric phenomenon that depends on charge.
• There are two kinds of electric charge: positive and negative.
• Electrons (negative) and Protons (positive) are the basic charges of ordinary matter.
• The SI unit of electric charge is Coulomb (C). One coulomb is equal to the total charge of 6.25 x 10¹⁸ electrons.
• Protons and Neutrons are found in the nucleus of an atom. Electrons surround the nucleus.
• Electrons are free to move and are responsible for chemical interactions.
• Neutrons are neutral and have no charge.
• Atoms have as many electrons as protons, so the atom is neutral with zero net charge.
• o If an Electron is removed from an atom, the atom is said to be positively charged and is called a positive ion.
• If an Electron is added to an atom, the atom is said to be negatively charged and is called a negative ion.

Electrical Force

• Electrical Force is the force between charged particles.
• The electrical force can be repulsive and attractive: alike (same)charges repel, opposite charges attract.
• The electrical force is a vector quantity (magnitude and direction).
• As the case with all forces, the electrical force is measured in Newton (N).

Coulomb's Law

• Electrical forces may be either attractive or repulsive,
• But gravitational forces are always attractive.

Exercises

Exercise 1

Exercise 2

Exercise 3

Exercise 4