6A10.XX Micro Bank


Reflections from flat mirrors, lenses


Coins appear to drop through a funnel that should be unable to pass the coins. The coins end up in a box, apparently shrunken.

In reality, the funnel doesn't exist, and the actual structure of the bank is cleverly obscured by mirrors. A lens (probably diverging) in front of the box makes the coins appear smaller.



  • [1] Micro bank
  • Coins


  1. Show students the micro bank.
  2. Put coins in.


Additional Resources


  • PIRA 6A10.XX, 6A60.XX


  • You can try this at home, but don't blame us if you get hurt somehow!

Last revised

  • 2020


Related AV

  • There's a video of the micro bank with the back removed so you can see the box where the coins go. The back opens up around 2:49.

Related demos


If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.