High Speed Coin Shrinking

Posted by rob on 12 June 2009
A quarter caught in the act of shrinking

A quarter caught in the act of shrinking

We recently had a chance to work with the fine folks at Intellectual Ventures to quantify some of what goes on with our coin shrinker. Using a bunch of neat gear (including an extremely high speed camera), we were able to learn all sorts of things about our amazing chamber of shrink. Here is some of what we learned:

  • The coin shrinks in just 30 to 40 microseconds. Even when filming at 100,000 frames per second, that’s just 3 or 4 frames of video!
  • By the time the coil begins to explode, the coin has already been shrunk for several microseconds!
  • The collapsing coin gets extremely hot: the thinnest part of the center of a quarter glows bright white-red for a few microseconds just after shrinking.
  • At one meter away from the spark gap, the shrinker generates a big bang: about 135 dB, or roughly as loud as a jet engine taking off from 100 meters away.
  • The magnetic field created by the coil is extremely strong: at 10 cm from the coil (just on top of the lid of the blast chamber) we measured a peak field strength of 0.22 tesla, or about as strong as a small neodymium magnet.
  • During the explosion, some of the bits of shrapnel fly past the camera’s view at about twice the speed of sound.
  • The edge of the coin moves about 1/4″ in 36 microseconds, or roughly 400 miles per hour!

There’s a lot more info over on Intellectual Ventures’ blog. More photos of the camera rig and actual shrinkage are available here.

A just-shrunk quarter, captured at 100,000 frames per second

Posted in: Electricity, Featured  

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