Electrical charge

- Before discussing electricity, it's important to first 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 attract or repel each other. For example, when I rub this 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 scientist 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 consist of three types of even tinier little particles called protons, neutrons, and electrons. Protons and electrons are particles which have equal and opposite and 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 an 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 center 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 course. 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 apart. 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 I rub the rubber balloon on the wool scarf, both of them are neutrally-charged. But when I rub the balloon on the scarf, the friction causes a 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 I leave them together long enough, eventually enough of those extra electrons in 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 video right now, thanks to electricity, because computers and the internet rely on the movement of those tiny little electrons to function. As an electrical engineer, I'll think of myself like a plumber. But rather than using pipes and valves to direct the flow of water, I design electronic circuits to control the movement of electrons, to put them in the right place at the right time to do something useful.