One tuning fork with tuned cavity, drives another.

Tuning Forks. Both Tuning Forks (mounted on sounding boxes) are rated at the same frequency. Strike one tuning fork so that it rings loudly. Grab it to stop it. The second tuning fork is heard to be ringing.
UCB Index: 
B+20+15
PIRA Index: 
3B70.10
Demo Diagram: 

Popularity: