The saying ‘bigger is better’ has taken the nation by storm, whether it’s describing the size of your phone or your television. But for the people over at Physics Girl, they’ve taken a liking to the exact opposite of that perspective, shrinking. Now you may remember “Honey, I Shrunk The Kids” where an inventor’s shrink ray miniaturized his children, but this shrinking isn’t movie magic. Using a capacitor, a coil and some electricity they are able to actually shrink a quarter to a notably smaller size. Although it isn’t truly shrinking, but more compressing, it gives the illusion that the quarter has been shrunk down.
Electromagnetic Shrinking
You may be wondering how it works, and it’s probably not how you’d think. First, a high voltage power supply must charge up a capacitor to 8,000 volts. Then a coin is wrapped around a copper coil which is attached to the capacitor, and the electricity is run through. As the electricity runs through it, it not only shrinks the coin, but also nearly destroys the copper coil, causing an explosion. The current running through the coil creates a magnetic field that runs nearly parallel through the coil wrapped quarter. When the coil is at peak capacity it has around 50,000 Amps running through it, which is around the same amount produced in a lighting strike. By increasing the magnetic field, it induces currents in nearby conductors, which be more formally summarized by Faraday’s law of induction. That nearby conductor is the quarter, and although most of the current runs around the quarter, it is subject to Lorentz’s Force. When the magnetic field is met with the charges inside the quarter, it causes the coin to compress from force moving inward. Now this is not an experiment that you’ll be able to try at home, as it is difficult and dangerous to attempt without the proper equipment and experience. To get a better visual of all of this happening, check out Physics Girl’s video. If you could shrink any conductible item, what would you choose? And if you really want a shrunken coin for yourself, you can purchase one online.
