Fundamentals of Electricity and Circuit Principles

Basic Electrical Concepts

Voltage (Tension)

Voltage (also known as Tension or electromotive force) is the energy with which a generator is able to push electrons through a circuit.

Electric Current (Intensity)

Electric Current (or Intensity) is the number of electrical charges flowing through a circuit per unit time. It is measured in amperes (A).

Resistance

Resistance is the opposition a material offers to the flow of electric current. Materials with high resistance make it difficult for electricity to pass through. Resistance is measured in ohms (Ω).

Electric Power

Electric Power indicates the rate at which a device performs its function. The power consumed by a receiver is directly related to the voltage and current that feed the circuit. Power is measured in watts (W). The kilowatt (kW), equivalent to 1000 W, is also commonly used. Power is the ability of a receiver to perform its function more efficiently and/or faster.

Laws and Circuit Configurations

Ohm's Law

Ohm's Law states that the intensity of electric current flowing through a circuit is directly proportional to the voltage applied and inversely proportional to the resistance offered. The formula is: I = V / R.

Series Circuits

In a series circuit, the current (intensity) is the same throughout the entire circuit. The total voltage across the circuit is equal to the sum of the individual voltage drops (e.g., V1 = I * R1). The total resistance is the sum of all individual resistances.

Parallel Circuits

In a parallel circuit, the voltage (tension) is the same across all branches of the circuit. The current (intensity) varies depending on the resistance in each branch. The expression for current in a branch is: I1 = V/R1.

Total Resistance in Parallel Circuits

• For N = 2 resistors: Rt = (R1 × R2) / (R1 + R2)
• For N > 2 resistors: 1/Rt = 1/R1 + 1/R2 + ... + 1/Rn

Electrical Measurement Devices

There are various devices for measuring electrical magnitudes in any circuit:

• Voltmeters: Used to measure voltage (tension).
• Ammeters: Used to measure current (intensity).
• Ohmmeters: Used to measure resistance.
• Wattmeters: Used to measure power.

These measuring devices can be either analog or digital.

Effects of Electric Current

Joule Effect

The Joule Effect transforms electrical energy into heat. Applications include incandescent lamps and fuses.

Incandescent Lamp

In an incandescent lamp, light is produced by passing electricity through a filament. The filament heats up to temperatures between 2000 and 3000 °C, causing incandescence. As a result of this high temperature, the filament emits intense light radiation.

Short Circuit

A short circuit is an accidental condition in an electrical circuit where electric current flows directly from one pole of a generator to another without passing through any receiver. This causes a large release of heat, which can be dangerous.

Fuse

Fuses are among the oldest protection elements used in electrical circuits, based on the Joule Effect. A fuse detects an increase in temperature and melts, thereby opening the circuit, stopping the current flow, and preventing further damage.

Electromagnetism

Electromagnetism Defined

Electromagnetism is the science that studies the relationship between electricity and magnetic fields.

Electromagnets

An electromagnet is a temporary artificial magnet that only acts as a magnet when electric current flows through it. It typically comprises a copper coil and an iron core.