The city won’t approve you putting a henchman-wide spotlight on the roof of your house, so what’s a Bat-Fan to do if you want to show off the Bat-Signal? Grab a magnet, some copper wire, and a little physics knowledge to craft a simple but Wayne-worthy electric motor.
There are no strings in the GIF above from AstroCamp — to get a wire to spin around all you need is a strong (e.g., neodymium) magnet, a AA battery, and the aforementioned wire.
What makes the motor run is the interaction between the electricity flowing through the wire and the magnetic field invisibly exuding from the magnet. Electrons flowing from the positive terminal of the battery, through the wire, to the magnet, and finally to the negative terminal experience what’s called the Lorentz Force, as the diagram from AstroCamp shows below:
The Lorentz Force is a force that a charged particle (like an electron flowing from a battery) experiences moving through a magnetic field. For this Bat-Signal battery, the current isn’t very big (q*v), but the magnetic field is relatively large (B). With the current and magnetic field in a specific orientation in space (the little arrows or vectors above the equation letters), the result is a force large enough (F) to spin the wire around in a circle.
It looks complicated, but there’s a simple rule you can use to remember this little interaction: the right-hand rule. If you orient your right hand with the thumb in the direction of the current and your fingers pointing out along with the magnetic field, the Lorentz Force will come out of your palm. Try it for this mini-Bat-Signal…it works!
Vengeance, the night, physics!