Fundamentals of Electricity: Atoms, Circuits, and Ohm's Law

The Atom

The atom is the fundamental unit of matter, consisting of a nucleus containing protons and neutrons, surrounded by orbiting electrons.

Atomic Structure

Atoms are composed of negatively charged electrons, positively charged protons, and neutrons, which carry no charge.

Electrical Charge

Electrical charge is a property of matter responsible for electrical phenomena. Bodies with the same charge repel each other, while those with opposite charges attract.

Static Electricity

Static electricity occurs when electric charges remain at rest and do not move along a material.

Electric Current

Electric current is defined as the continuous movement of electrons.

Conductors and Insulators

• Conductive Materials: Substances that allow the passage of electric current.
• Insulating Materials: Substances that do not allow the passage of electric current.

The Electric Circuit

A circuit is a set of interconnected elements through which electric current flows. It consists of a generator, conductive wires, a switch to open or close the path, and receivers.

Generators and Receivers

Generators originate and provide electrical energy. Types include:

• Batteries (chemical energy)
• Alternators or dynamos (mechanical to electrical energy)
• Solar cells (solar energy)
• Hydrogen cells (hydrogen and oxygen energy)

Conductors transport the energy, while receivers convert it into heat, light, or movement.

Control and Protection Elements

• Control Devices: Manage the flow of current by interrupting or diverting it.
• Protective Devices: Prevent damage to the installation or harm to people.

Fundamental Electrical Quantities

• Charge (Q): The amount of electricity stored in a body, measured in Coulombs.
• Tension or Voltage (V): The energy provided by a generator that puts the charge into motion, measured in Volts.
• Current Intensity (I): The number of electrons passing a given point in a circuit per second, measured in Amps (A).
• Electrical Resistance (R): The opposition exerted by circuit elements to the passage of current, measured in Ohms (Ω).

Measuring Instruments

• Voltmeter: Measures voltage; connected in parallel with the generator.
• Multimeter (Polimeter): Used to measure various electrical quantities (voltage, current, resistance) across different scales.
• Ammeter: Measures current intensity; connected in series with the receiver.

Ohm's Law

Ohm's Law defines the relationship between voltage, current, and electrical resistance, expressed as: V = I × R. These values are directly proportional.

• I = V / R
• R = V / I

If the voltage doubles, the intensity also doubles; if the voltage is reduced, the intensity is reduced accordingly.