Fundamentals of Electricity: Atoms, Circuits, and Current

The Atom: The Building Block of Electricity

Understanding the atom is important for an effective study of electricity. Everything around us is made of atoms. In the middle of each atom is a nucleus, which contains two kinds of tiny particles called protons and neutrons. Orbiting the nucleus are even smaller particles called electrons.

Atomic Structure and Charge

A model of the atom is similar to our solar system. The nucleus is in the center of the atom, like the sun is in the center of the solar system. The electrons orbit the nucleus, much like the planets orbit the sun.

• Protons have what we call a positive (+) charge.
• Electrons have a negative (-) charge.
• Neutrons have no charge; they are neutral.

Normally, atoms are neutral. That is to say, they have the same number of protons as electrons. However, electrons can move from one atom to another. An atom that loses electrons has more positive charges (protons) than negative charges (electrons), making it positively charged. An atom that gains electrons has more negative than positive particles, giving it a negative charge. A charged atom is called an ion.

Conductors and Insulators

Materials can be classified based on how easily electrons can move through them.

Conductors

Conductors are materials that allow electrons to flow through them easily. Examples include:

• Silver
• Copper
• Gold
• Aluminum
• Iron
• Steel
• Brass
• Bronze
• Mercury
• Graphite
• Dirty Water
• Concrete

Insulators

Insulators are materials that resist the flow of electrons. Examples include:

• Glass
• Rubber
• Oil
• Asphalt
• Fiberglass
• Porcelain
• Ceramic
• Quartz
• Dry Cotton

Understanding Electric Circuits

An electrical circuit is a closed loop formed by a power source, wires, a fuse, a load, and a switch. When the switch is turned on, the electrical circuit is complete, and current flows from the negative terminal of the power source, through the wire to the load, and back to the positive terminal.

Any device that consumes the energy flowing through a circuit and converts that energy into work is called a load. A light bulb is one example of a load; it consumes electricity from a circuit and converts it into work—in this case, heat and light.

Key Elements of an Electric Circuit

• Power Source: Supplies electric energy (e.g., batteries, cells).
• Load: Transforms electric energy into another type of energy, such as heat (resistor), light (light bulb, lamp), or motion (motor).
• Wires: Provide a path for the current, usually made of copper.
• Switch: Allows you to open or close the circuit, controlling the flow of current.
• Fuse: A safety device designed to protect other components from damage. If the current rises above the fuse's rating due to a malfunction or short-circuit, the fuse will blow and disconnect the circuit.

Electric Current and Circuit States

Current is the flow of electrons in an electric circuit. Connected to a source of voltage, an electric lamp circuit allows this flow to happen.

• A circuit with no path for electrons to travel is called an open circuit.
• A circuit with a complete path for electrons to travel is called a closed circuit.