PURPOSE: To blast a cola can into two pieces using electromagnetism.

DESCRIPTION: A 400 microfarad capacitor is charged to 3000 volts (1.8 kilojoules) and discharged through a three-turn coil into which an aluminum soft drink can has been positioned, as shown in the detail photo at the center. With the circular windows open, as in the photograph at the left, the two pieces of the can will be blasted over thirty feet to the sides of the large lecture hall. Charging the capacitor to less voltage results in a can with a "waist," as seen in the photograph at the right.

This device can be explained in two distinct ways:

(1) The rapidly rising current creates a rapidly rising magnetic field along the axis of the coil, which in turn induces an electric field going in circles inside the coil. The induced electric field causes an electron current in the can which experiences a vxB force in the magnetic field of the coil, causing the can to break into two pieces which are blown to the opposite sides of the lecture hall.

(2) The plasma "theta pinch" phenomenon occurs when the capacitor is discharged. This effect causes radiation pressure on the can which breaks it in two and blasts apart the two halves.

This is an UNFORGETTABLE DEMONSTRATION. A must when you cover electromagnetism.

SUGGESTIONS: This device may be DANGEROUS if not operated properly. You must obtain permission from a Lecture-Demonstration staff member before attempting to operate it by yourself.

REFERENCES: (PIRA 5K20.65) See Demonstration Reference File for a very nice article by Prof. Alan Da Silva of the University of Maryland Plasma Physics research area, who designed this device and describes its theory.

Click here for a nice slow-motion video of the can crusher at Wesleyan University, compliments of Vacek Miglus.

The web site http://hibp.ecse.rpi.edu/Can_Crusher/home.html contains a drawing and animation showing how the RPI electromagnetic can crusher works.

EQUIPMENT: Electromagnetic can crusher.

SETUP TIME: None, if you know how to operate it.