Monday, 22 July 2013 10:13

## K2-62 CAN SMASHER - ELECTROMAGNETIC Featured

• ID Code: K2-62
• Purpose: Blasts a soda 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. With the circular windows open, 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."

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) A type of "theta pinch" phenomenon. More information on this is available from Wikipedia. Another way to understand this is that the induced current around the can is opposite to the current in the primary coil, since it is opposing the change in flux. These concentric opposite currents repel each other, so the can is pinched and torn apart and ejected out the sides.

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

This video, from the Video Encyclopedia of Physics Demonstrations, shows the operation of the can crusher with an animation illustrating (1) the electron current in the coil, (2) the vector magnetic field that it creates, (3) the induced electric field within the coil created as the coil current rapidly rises, (4) the electron current circling in the can created by that induced electric field, (5) and the vxB force on the electrons moving around the can.

Following a description of the crusher electronic components, the animation is displayed. The animation may be stopped so that the directions can be studied in detail for the five (5) quantities listed above. Using the left hand rule (for electrons) the directions can be verified; note that according to Lenz's law the direction of the electron current induced in the can must be in the opposite direction to the electron current in the coil.

Note that the magnetic field at either end of the coil possesses both an axial and a radial component; the electron current in the can is entirely azimuthal. Using the left hand rule to determine the direction of the cross product of the electron velocity and the magnetic field, it can be seen that the axial component of the magnetic field leads to an inward force, crushing the can, while the radial field component leads to an axial force, away from the plane of the coil at both ends of the can, causing the two parts of the can to move rapidly away from the coil. (In the large lecture hall the two parts of the can will be blown to the sides of the lecture hall.)

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.

• Availability: Available
• Loc codes: FS1
• #### K2-01 EARTH INDUCTOR

Induces an emf by moving a coil through Earth's magnetic field Read More

• #### K2-03 FARADAY'S EXPERIMENT ON INDUCTION

Demonstrates the induction between two coils Read More
• #### K2-04 FARADAY'S EXPERIMENT - EME SET - 20, 40, 80 TURN COILS

Shows that the induced current is proportional to the number of turns in the secondary coil Read More

• #### K2-12: SELF-INDUCTION - DEMOUNTABLE TRANSFORMER

Demonstrate back-EMF in an inductor Read More
• #### K2-21: RUHMKORFF INDUCTION COIL

Demonstrate induction of a very high voltage using a small voltage source Read More
• #### K2-22 INDUCTION COIL WITH LIGHT BULB

Demonstrates magnetic induction with 110 VAC Read More

• #### K2-25: MUTUAL INDUCTION - DEMOUNTABLE TRANSFORMER

Demonstrate mutual induction and to show the effect of various core materials Read More
• #### K2-26: MUTUAL INDUCTANCE STANDARD

Demonstrate the standard for mutual inductance Read More
• #### K2-27: MUTUAL INDUCTION - M12 eq M21 MEASUREMENT

Demonstrate that the mutual inductance between two coils is independent of which one is the primary Read More
• #### K2-28: DEMOUNTABLE TRANSFORMER - 10 KV ARC

Demonstrate that a large voltage increase is attainable using a transformer Read More
• #### K2-29: COIL AND MAGNET WITH LED SENSOR

Demonstrate that the sign of the induced voltage depends on the direction of the field as well as whether the Read More
• #### K2-40: MAGNETIC ACCELERATOR

Demonstrate magnetic potential energy Read More
• #### K2-41: LENZ'S LAW - ROLLING RODS

Demonstrate eddy currents and Lenz's law Read More

• #### K2-44 EDDY CURRENT PENDULUM

Shows the damping of pendula due to eddy currents Read More
• #### K2-45: EDDY CURRENTS - MAGNET AND SOFT DRINK CAN

Demonstrate eddy currents and Lenz's law Read More
• #### K2-46: MAGNET LEVITATION ABOVE SPINNING DISC

Demonstrate Lenz's law in a dramatic way Read More
• #### K2-47: SPEEDOMETER MODEL

Demonstrate operating principle of some speedometers Read More
• #### K2-48: EDDY CURRENT MOTOR`

Show the use of eddy currents in producing a motor with few moving parts and no electrical brushes Read More
• #### K2-49: MAGNETIC STIRRER

Illustrate how a magnetic stirrer works Read More
• #### K2-61 THOMSON'S COIL

Demonstrates a number of concepts in magnetic induction Read More
• #### K2-62 CAN SMASHER - ELECTROMAGNETIC

Blasts a cola can into two pieces using electromagnetism Read More
• #### K2-63: DISPLACEMENT CURRENT MODEL

Illustrate the geometry for displacement current Read More
• #### K2-64: UNIPOLAR GENERATOR

Demonstrate unipolar generation of DC voltage, which may involve an explanation other than electromagnetic induction Read More
• #### K2-65: INDUCTION AND CAPACITOR FLASHLIGHT

Demonstrate a weird but high-tech method for constructing a flashlight Read More
• 1