Understanding Static Electricity, Electric Circuits, and Ohm's Law

The unit load in the International System of Units is the coulomb (C). Friction between different objects or the movement of fluids causes charges to accumulate on the surface of insulating materials or conductive materials that act as insulators. These charges cannot move freely as they do in electrical currents; therefore, this phenomenon is called static electricity.

Electric Circuits: Components and Function

An electric circuit consists of these basic elements: a generator, a receiver, conductors, and control devices. The conventional current flows from positive to negative, although in reality, the current consists of electrons moving in the opposite direction.

Energy Loss and the Joule Effect

The movement of charge through a conductive material is not effortless. Electrical energy is lost as heat; this phenomenon is known as the Joule effect. For example, light bulbs have a metallic tungsten filament that heats up when an electric current passes through it.

Batteries and Voltage

Batteries are made up of substances that cause a reaction, resulting in moving charges. The voltage, or electromotive force, of a generator indicates the charge that flows through each electrical circuit. In the International System of Units, voltage is measured in volts (V).

Electric Current Intensity

The intensity of electric current is determined by the amount of charge that passes through a circuit at any given time. Electric intensity is measured in amperes (A), and the apparatus used to measure it is called an ammeter. The intensity depends on both the voltage and the amount and type of receivers, as well as how they are connected.

Electrical Power: Voltage and Intensity

As the voltage of a generator expresses the energy that carries the charge, and the intensity expresses the number of circulating charges on the circuit at every moment, the result is called electrical power, and in the International System of Units, it is measured in watts (W). The formula is: Power = Voltage · Intensity. Most appliances have their power consumption indicated.

Calculating Electrical Consumption

As electric power is equivalent to the energy a device consumes every second, you can calculate the electric consumption over a period by multiplying power by the time of operation. The formula is: Energy = Power · Time

Resistance and Ohm's Law

The resistance of a receiver is measured in ohms (Ω) and is not necessarily the same under all conditions. Resistance = Voltage / Intensity. This relationship is called Ohm's Law. Resistance can be measured with an instrument called an ohmmeter.

Safety Measures: Fuses and Circuit Breakers

Fuses and circuit breakers in many installations are protective measures to prevent disasters from a short circuit.