We’re going to build on the quick ‘n’ easy DC motor to make a tiny rail accelerator (any larger, and you’ll need a power plant and a firing range and a healthy dose of ethics.) So let’s stick to the physics of what’s going on in this super-cool electromagnetism project. This project is for advanced students.


Here’s what we’re going to do:


We’re going to create two magnetic fields at right angles (perpendicular) to each other. When this happens, it causes things to move, spin, rotate, and roll out of the way. We’re going to focus this down to making a tiny set of wheel zip down a track powered only by magnetism. Ready?


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Materials:


  • cardboard
  • aluminum foil
  • hot glue
  • scissors
  • paper clip or wire coat hanger
  • two very small, strong disc magnets
  • 9V battery with clip
  • 2 alligator clip leads
  • pliers


Download Student Worksheet & Exercises


Did you notice how this rail accelerator is really just two of the ‘quick ‘n’ easy DC motors connected together? The wire is now the aluminum rail, and the magnetic field in the rail create a force perpendicular gold disk’s magnetic field. These two magnetic fields interact, causing the little wheels to roll. Which is why if you have the wheels on ‘backwards’ (or your battery connected backwards), your wheels will roll toward (instead of away) from you.


Troubleshooting: If you drop your wheels from too high up, you’ll knock the axle off-center and the wheels won’t roll. If your wheels still don’t roll, flip one of the magnets around (they must be in opposite directions for this to work!). Also make sure you’ve got a fresh 9V battery and good electrical connection between your clips and the track.


Exercises


  1. Do the magnets need to be opposite in order for this to work?
  2. Why do the wheels move?
  3. Which track works the best?

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