Understanding Electricity and Electrical Circuits

Posted on Jan 28, 2025 in Electronics

Electricity

Electricity: Power is a form of motion. It is electrons. Matter is formed by molecules. The nucleus is composed of protons with positive mass and electric charge, and neutrons.

Electric Charge

One can say a body is negatively charged when it has an excess of electrons, and positively charged when it has a defect of electrons. In the neutral state, the number of electrons equals the number of protons. The electric charge of a body is the excess or deficiency it has of electrons, and is measured in coulombs.

  • 1e = 1.6 x 10-19C
  • 1C = 6.24 x 1018e

V = Potential difference is the difference in energy that exists per unit charge in two points. It is measured in volts.

Electrical Resistance

Electrical resistance is the resistance of a conductor to the passage of electrons.

Electric Current

Electric current is the movement of electric charge through a conductor. Conductors contain a large quantity of free electrons.

For electric power to exist, the following are needed:

  1. Free electrons – the more free electrons, the more current passes.
  2. Potential difference to attract and repel the electrons.

There can be two types of current:

  1. Continuous, such as batteries.
  2. Alternating current (AC), generated by alternators.

Current Intensity

Current intensity (I) is the quantity of electric charge that passes through a section of a conductor, measured in Amperes.

Elements of an Electric Circuit

a) Electric Generator

An electric generator produces electrical energy.

  • Alternators: are AC generators that transform mechanical energy into alternating energy.
  • Dynamos: generate continuous current, transforming mechanical energy continuously.
  • Batteries: produce a chemical reaction in which energy is transformed into continuous current.
  • Photovoltaic cells: are semiconductors that transform light energy into electrical energy.

Connection of Generators

Batteries can be associated to achieve differences in power or duration. They can be associated in two ways:

  • In series: generators are connected to each other, forming a chain. The poles of the generators should be connected to the opposite poles. They should have the same voltage and current. If one is not connected, it will not consume.
  • In parallel: the generators are connected by their extremes to the same circuit. The same poles are joined in parallel. If a battery does not have the same voltage, a short circuit occurs.

Electric Receiver

Electric receivers are elements that transform electrical energy into other forms of energy.

  • Motors: are devices that transform electrical energy into mechanical energy.
    • DC motors: use direct current.
    • AC motors: need alternating electric energy.
  • Lamps: are devices that convert electrical energy into light.
  • LED (Light Emitting Diode): A diode is an element that only allows energy to pass in one direction. An LED converts electrical energy into light. The short pin indicates the anode.
  • Buzzers: transform electrical energy into sound energy (with continuous current).
  • Speakers: transform electrical energy into sound energy (with alternating current).
  • Resistances: reduce the passage of current.
  • Electromagnets: transform electrical energy into mechanical energy.

Control Elements

  • Switch: is an operator that opens or closes an electric circuit.
  • Button: is a temporary switch that remains open or closed in a circuit when it is acted upon.
  • Commutator: when you click, it allows the current to pass through one path.
  • Crossover switch: switches that are used to activate the same receiver from two or more sites.
  • Cross-dresser: used to reverse the direction of an engine’s spin.

Connection of Control Elements

If you connect several switches in series, the current will flow when all are closed. But if one or more are open, no current will flow through the circuit.

Protection Elements

Fuse: is an element of protection for all devices that protect the electrical circuit from overloads that can occur. Protective fuses are elements that are inserted in a series circuit to protect against excessive consumption.

Short circuit: when you close a circuit without a receiver, a very large current flows, and the electrons do not see any difficulty (resistance) to reach the positive terminal. This generates a short circuit that can burn the conductor.