Is It Electric or Magnetic? Depends on Where You Stand

If you took introductory physics, you learned astir the “fundamental forces.” It goes thing similar this: All interactions are the effect of 1 oregon much of 5 basal forces: beardown nuclear, anemic nuclear, gravity, electric, and magnetic. “Doing physics,” then, means identifying the forces successful play.

There’s a problem, though, which mightiness not person been mentioned: The forces you observe beryllium connected your vantage point—your “frame of reference.” Look retired the window. Trees, houses, lawns—they’re each stationary, right? But look astatine that aforesaid spot from abstraction and it’s moving a 1000 miles an hour. It looked inactive to you earlier due to the fact that you were moving with it.

We person this aforesaid occupation with electrical and magnetic fields. Depending connected your notation frame, what appears to beryllium a magnetic unit from 1 spot appears to beryllium an electrical unit from another.

Is your encephalon melting yet? Just wait—it gets adjacent weirder. To recognize what’s going connected here, let’s archetypal look astatine electrical and magnetic forces successful isolation.

The Electric Force

See each that worldly astir you? Everything. It's each made of conscionable 3 things: protons, electrons, and neutrons. That's benignant of chaotic erstwhile you deliberation astir it. Two of these cardinal particles person an electrical charge: the negatively charged electron and the affirmative proton.

If an entity has much electrons than protons, it volition person a nett antagonistic charge. So, that sock successful the dryer that clings to everything? It picked up other electrons by rubbing against different clothes. If an entity loses electrons it has a affirmative charge.

We tin cipher the electrostatic unit betwixt 2 charged objects with Coulomb’s law. This says that the unit betwixt them depends connected the merchandise of their charges and however acold isolated they are. To illustrate, I built this high-tech contraption below, which has 2 small foam blocks hanging connected strings. I gave them some a antagonistic charge, which means they’ll repel each other. Check it out: