Slinky Resonance

Move your hand up and down super slowly. This is NOT the resonant frequency.

Move your hand up and down very quickly. This is also NOT the resonant frequency.

Then move your hand just right so that you are moving at the resonant frequency. Your hand should be moving very little in amplitude, while the slinky moves a lot!

Note: You can also try this as a transverse wave in the air. You may also do this on a smooth surface.

Pendulum Resonance

Swing your hand super slowly. This is NOT the resonant frequency.

Swing your hand very quickly. This is also NOT the resonant frequency.

Then move your hand just right so that you are moving at the resonant frequency. Your hand should be moving very little in amplitude, while the pendulum moves a lot!

Note: Ask students about applications for pendulum resonance. Guide them to thinking about how they pump their legs on a swing. If they pump too quickly or too slowly, they won't be at the resonant frequency and they won't get to swing as high.

Sound Resonance

With tuning forks both playing the same frequency (make sure you don't have any attachments on one of the forks), place the tuning forks so they are oriented with both open ends of the wooden boxes facing each other.

Strike just one tuning fork. Allow the sound to reverberate for just a second or two, then place your hand on top of that tuning fork.

You should be able to hear the sound still. Place your other hand on top of the tuning fork that was not struck. The sound should stop.

Note: Students should be really quiet for this to be heard well. If the whole class can't hear it well, it would do well to try it in small groups.