# Electromagnetic Induction Basics Electromagnetic induction - it's really useful! From power stations to your plug, this transfer of energy is only really possible thanks to the effect of magnetic fields, as well as their ability to **induce** an electromotive force. This'll focus mainly on the high-school applications of electromagnetic induction. And for those who want to do something physics-related further on, ever wondered why induction actually works? Read on to learn more! NOTE: This part is unfinished. Duty calls! Fun next, unfortunately. ![[e&mcomic.png]] *The ballad of E&M progression.* # EM Induction Basics - Faraday's Law and the Right Hand Rule Magnets weren't always called 'magnets'. There's a reason why the lodestone is still seen as a means of waypoint - back in ancient times, philosophers, scientists, the odd shepherd would stumble upon a really curious form of rock, which they called *magnetite*. Its attraction to iron and other types of ore interested the greeks; as a result, they were able to rely on this property as **lodestones**; in fact, Chinese 'geomancers' - a pseudo-earth scientist, would harness this property to create the world's first primitive compasses. During the 1800s, [Michael Faraday](https://www.faraday.cam.ac.uk/about/michael-faraday/) was experimenting with coils. He found that if you placed two coils in a magnet and ran a current through one of them, there would be a current in the other coil, unconnected to a power source. %%get diagrams. coils are difficult to draw on trackpad, but when has that stopped you?%% Running more tests, he soon found that changing the strength of magnetic field when running a conductor through it would also change the electric field. Since this led to a work being done on the electric field of the coil, there would be a constant force throughout the area of influence of the electric field, which the other coil would fall into. This force is the **electromotive force** (*emf*), which leads to the current as charges within the wire are compelled to move. In addition, he found that the induced emf was proportional to the number of turns of the coil in which the emf was induced, giving rise to the equation: $\epsilon = N \frac{d\Phi}{dt}$ Which is Faraday's law of Electromagnetic Induction # Lenz's Law Faraday's discovery made waves within the physics world of his time. He would be the inspiration for scientists like Maxwell, Lorentz, and for the purposes of this section, Heinrich Lenz. It states that: > The current induced by a change in magnetic flux must oppose this change and exert an electromotive force which opposes the motion. Which is a fancy way of saying that "you can't have unlimited energy because the [[Power, Work Done and Energy#Mechanical Energy - Conservation of Energy|law of conservation of energy]] applies, so induced current will go in the opposite direction of the magnetic force that induces it." In other words, add a 'minus' sign to Faraday's law to get Lenz's Law. $\epsilon = N \frac{d\Phi}{dt}$ # TransformersBASICS Remember the coil experiment Faraday did? Well, consider this the 'continuation' to this.