It’s important to understand electrical charge because electricity is simply the movement and accumulation of electrically charged particles. If you’ve ever been shocked when you touch a doorknob after shuffling across the carpet on a dry day then you’ve felt the effect of electrical charge. Hundreds of years ago, some clever scientists noticed that when they rubbed certain objects together, it would cause those objects to either attractor repel each other. For example, when we rub this a balloon on a wool scarf, they become attracted to each other and they stick together. The cause of this strange phenomena remained a mystery for a really long time but eventually, the scientists realized that the reason the scarf and balloon are attracted to one another after being rubbed together is because the friction creates an imbalance of electrical charge between those objects.
All objects are made of tiny little building blocks called atoms which are way too small to see and each of those atoms consists of three types of even tinier little particles called protons, neutrons and electrons. Protons and electrons are particles which have equal and opposite electrical charges. We say that protons are positively charged and that electrons are negatively charged. The neutrons don’t have any electrical charge so we call them neutral. The amount of charge in an object can be measured using a unit called coulombs which is abbreviated with a capital letter C.
One coulomb is equivalent to a certain number of positively charged protons and negative one coulomb is equal to the same number of negatively charged electrons.
The proton and neutron particles are clumped together at the centre of each atom in what’s called the nucleus. Now, while these protons and neutrons are usually stuck together in the nucleus, the electrons have a lot more freedom to move around and that movement of electrons is what we’ll be focused on throughout this topic.
The electrons float around the nucleus of the atom and they can even leave the atom completely and travel to other nearby atoms. When two similarly charged particles get close to each other, so either two protons or two electrons, they repel each other and are forced to part. However, when two oppositely charged particles come together, a positively charged proton and a negatively charged electron, they’re attracted to each other.
When an object has an equal amount of positive and negatively charged particles, we say that it is neutrally charged because all of those charges balance out. Before we rub the rubber balloon on the wool scarf, both of them are neutrally charged but when we rub the balloon on the scarf, the friction causes of bunch of electrons from the atoms in the scarf to jump over to the atoms on the balloon. This happens because the rubber material has a stronger desire for electrons than wool so the balloon steals some of those electrons from the scarf. Now, there are more electrons than usual on this balloon so overall, it’s negatively charged and since the scarf has just lost a bunch of negatively charged electrons when they jumped over onto the balloon, the scarf now has an overall positive charge compared to the balloon. Since the balloon and scarf now have opposite overall charges, they’re attracted to each other. Though if we leave them together long enough, eventually, enough of those extra electrons on the balloon will find their way back to the scarf so that both objects are neutrally charged again and no longer attracted to each other. When those little electrons build up and move around in one place or move from one place to another, we call that electricity and you’re watching this topic right now thanks to electricity because computers and the internet rely on the movement of those tiny little electrons to function. As electrical engineer, w’ll think of a plumber but rather than using pipes and valves to direct the flow of water, we design electronic circuits to control the movement of electrons to put them in the right place at the right time to do something useful.