User Tools

Site Tools


This is an old revision of the document!

Can Crusher


A capacitor is used to produce an extremely high (but short lived) current around a tin can. This sudden change in flux causes an opposing current to be set up in the tin can. This current, acted on by the original magnetic field set up by the coil, causes a strong Lorentz force to be experience around the circumference of the can, evenly crushing the can inwards.


This demonstration shows the action of Lorentz force in a dramatic fashion. This also effectively illustrates how energy can be stored in capacitors and can also be used to talk about RC circuits. (as an example of an RC circuit with a very short time constant.)



Place wooden platform over the PVC pipes covering the capacitor ends. This part is tricky, you can't 'slot' the platform on, it needs to be lifted and lowered onto the PVC pipes from above. Attach the switch and coil to the capacitor leads as pictured below. Place the can inside the coil. If necessary, it can be fixed in place with some tape.

Once everything is hooked up, you're ready to run the demonstration.

  1. Unclip the wire short from the terminals. If for whatever reason they were not already in place, short the capacitor with the discharge wand.
  2. Connect the power supply to the terminals.
  3. Plug the power supply in, (TODO: is following the voltage with the knobs faster?)
  4. Once the capacitor is charged to 3kV, remove the leads from the capacitor by pulling the attached strings. *Take utmost care in this step*; pull them off the terminals in a way that guarantees they have no chance of touching you. Place them on the ground away from each other.
  5. Turn off the power supply.


High voltage is used in this demo! Please ask for assistance from demo personnel if you have not operated this before. Always short the capacitor using the copper rod before touching anything with your hands to make sure it is fully discharged

Demo room information

Location —-
Maker Unknown
Current State Working
demonstrations/5_electricity_and_magnetism/5k_electromagnetic_induction/can_crusher/start.1554333326.txt.gz · Last modified: 2019/04/03 23:15 by demoroom