Study Guide

Physics Basics - Electricity and Magnetism

Electricity and Magnetism

We’re about to use our psychic powers to read your mind: Right now, you are... using an electronic device! Spooky, right?

Our impressive mind-reading skills aside, most people spend an inordinate amount of time using electronic devices and staring at screens. Don’t believe us? Next time you’re in a public place, play a little game we call: count the smart-phones. We like to see if we can reach 100. From phones, to computers, to televisions, to cameras, electronics are everywhere these days. But without the physics of electricity and magnetism, none of them would exist.

We use electricity to power and control those devices, and we use magnets to generate that electricity at power plants. If we spin a loop of wire near to a magnet, we create electricity in that wire. We can make that wire spin in many ways: from burning fossil fuels, to allowing the wind to push a turbine. So magnets and electricity are directly linked – one couldn’t exist without the other. Magnets are also found inside some electrical devices, including microphones and speakers, and giant ones are used in MRI scanners in hospitals.

Electricity is pretty big deal, because it powers everything from toasters to Mario Kart, and can cause us to get zapped if we’re not careful with it. But what exactly is electricity?

Electricity is actually made up of tiny particles called electrons. Anyone who’s studied chemistry knows electrons usually hang out around the outside of an atom with their friends. But in circuits, electrons are on a mission! It’s like the electrons have been sent to military school – they march in lines along electrical wires. Electricity flows in circles. We call that circular path a CIRCuit, because physicists are imaginative namers. The electrons start at a battery or power supply, finds their way to the components to power them, and then return back to the battery. This is as true in a vacuum cleaner as it is on the circuit boards of computers, though the path on a circuit board is a lot more windy.

We have various numbers that we use to describe circuits. If we take a look at the power supply for our favorite electronic devices, we’ll see terms like power, voltage and current – all things we’ll learn about in electricity and magnetism. Current is the rate of flow of electricity around a circuit. Voltage is like a measure of how much the electrons are being pulled around the circuit. And power is how much energy is being supplied by the circuit each second.

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