Ok-2 Echo Box With Choke Coupling
Published: Wednesday 15 March 2006 - Updated: Monday 28 March 2011
To illustrate the importance of symmetry in physics.
Cylinder and board as shown.
Click on pictures to enlarge.
A glass tube containing water is mounted above a screen with the cryptic message "ECHO BOX WITH CHOKE COUPLING". All letters with horizontal symmetry have been coloured blue.