Electrical Phenomena and Essential Electronic Components

Effects of Electric Current

The movement of electrons through conductive materials produces effects that have useful applications.

• Heat: The Joule Effect

  The movement of electrons through an electrical wire is slow and disorderly. Electrons often collide, increasing the temperature of the wire itself. The energy that an electrical current produces in the form of heat is called the Joule effect.

• Light Production from Electricity

  There are several ways that electricity can be used to produce light:

  • Incandescent Bulbs

    When an electrical current passes through the metallic filament of a bulb, it produces light. This phenomenon is called incandescence.

  • Fluorescent Tubes

    Inside a fluorescent tube, there is a metallic filament, usually tungsten. There is also an inert gas, such as argon, and a small amount of mercury. When an electric current passes through the filament, electrons are emitted into the inert gas. These react with the mercury, creating an invisible ultraviolet light. The phosphor coating inside the tube then transforms the UV light into visible light.

  • Light-Emitting Diodes (LEDs)

    A light-emitting diode (LED) has layers of semiconductor materials.

• Sound from Electrical Current

  We can transform electrical current into sound through the use of electromechanical devices, such as bells.

• Electromagnetic Effects

  Scientist Michael Faraday discovered the opposite effect. He observed that electricity could be generated by using a magnet and an electrical conductor. This principle allows us to build dynamos and alternators.

Numerical Examples

1. 1 y 0 = 10x10 = 100+- 5%

2. 2 y 2 = 22x10 = 220+- 5%

3. 3 y 3 = 33x10 = 330+- 5%

Electronic Components Explained

Resistors

A fixed resistance or resistor opposes the flow of electric currents. Its value, which we measure in ohms, is indicated by a code of colors and numbers.

Variable Resistors

The physical factors that affect resistance may be temperature or light.

• Thermistors

  Resistors that depend on temperature are called thermistors. There are two types of thermistors:

  • Negative Temperature Coefficient (NTC): The resistance decreases as the temperature rises.
  • Positive Temperature Coefficient (PTC): The resistance increases as the temperature rises.

• Light-Dependent Resistors (LDRs)

  An LDR is a resistor that varies according to the amount of light received. The resistance decreases as the amount of light increases.

Capacitors

Capacitors are electronic components that can store electrical energy.

We can determine the value of a capacitor with the equation: C = Q / V

• Q = number of electrical charges (coulombs)
• V = voltage (volts)
• C = the value of the capacitor measured in Farads (F)

Diodes

A diode is an electronic component made from semiconductor materials. It only allows electric current to flow in one direction. A diode has two electrodes: an anode (A) and a cathode (K). Electric current flows from anode to cathode.

Transistors

Transistors are basic components of electrical circuits. They are made from semiconductor materials and have three electrodes called the base, the collector, and the emitter.

There are two types of transistors: NPN and PNP.

Their main function is to amplify the electrical signal received.