This post aims to give you an overview of electronics and how electricity runs through a circuit. It gives a simple overview of electricity, including voltage, current and resistance.
An Introduction to Electronics
Electronics are used in practically every device you’ll find around the home, office and elsewhere. Electronics usually refers to circuits that use microchips, transistors and other little components, that work to form a piece of electronic equipment, like your TV, phone etc. The name electronics come from the word electron which is a negatively charged subatomic particle.
Every atom has at least one electron – electrons are flowing through everyday objects all the time. When we direct the electrons to flow in a unified direction, we get a current. Electrons can flow through some materials better than others. When a material allows current to flow easily, we call this a conductor. When a material doesn’t let current flow through it, it is an insulator. Metal is a conductor, and plastic is an insulator.
The typical wire is a long strand of metal coated in plastic. This is so the current can flow through the metal easily, but is contained within the wire – the electricity cannot pass through the plastic outer coating. On a printed circuit board, the current flows along the copper tracks, but cannot jump to other tracks across the plastic board.
Current and Resistance – Volts, Amps and Ohms
The current of a circuit is measured in amps (proper name ampere – symbol A) named after the French physicist and mathematician André-Marie Ampère. The force that drives the electrons through the circuit are called volts (symbol V), which are again named after the man who invented the battery, Alessandro Volta.
An example which is always used to get your head around the difference between amps and volts is that of a water pipe. The pipe in this analogy is the wire of the circuit, and the water is the flow of electrons. The pump that pushes the water is a battery (or mains socket). Current can be thought of as the amount of water that travels through the pipe per second. If a thin pipe is used, then only a small amount of water can flow through the pipe, whereas a bigger pipe allows a lot more water through.
Now if we were to partially block the pipe with something, we would cause resistance to the water flow. This resistance applies the same in electrical circuits and is measured in ohms with the symbol Ω (again this is named after someone – the German physicist Georg Ohm). A component that deliberately causes resistance is called a resistor. Resistors are used to limit current through a circuit. An example of this is when using an LED. If you are supplying the circuit with a voltage above the LED’s limit (common voltages in circuits are 5V, 9V and 12V), then the LED will simply die. A resistor is used to limit the current to a safe level that the LED can handle.
Current that flows into a component is not ‘spent’ in any way. The current that flows into components is always the same as the current that flows out. An important note is that a circuit must be a loop – it cannot just start and end. For example, if you are using a battery powered circuit, then the circuit must connect from the positive side to the components and back to the negative side (see image to the right).
That concludes this post. Hopefully you have a basic understanding of electricity and circuits. We’ll be following this post with a look at different types of power sources, different components and more.