Demonstrate wave interference and nodes in a plate Classes Used: Phys 101, 153

Wave interference, vibrational modes, nodes

To demonstrate wave interference and vibrational modes in a plate

Function generator Amplifier stereo with outpout Chladni plate (speaker and plate attatched) Plastic level Salt Plastic tray Brush

Attach the function generator output to the input at the back of the stereo labeled “Phono Right” Ensure the stereo is set to play the Phono input Attach the two cables from the back of the stereo to the speakers Select a frequency and test the speaker to check if the polarity is right (they only work one way) Place the plastic level in different directions on the plate and level the plate using the knobs on the triangular base Once it is level, sprinkle evenly onto the plate as shown in the images below Select one of the frequencies provided on the piece of paper and turn the volume up slowly A pattern will appear on the plate showing the plate's nodes at the respective frequency Now change the frequency to display other modes

Use the plastic tray provided to prevent salt from making a mess More salt needs to be added after frequency changes as it bounces off the plate If there is uneven salt distribution, remove salt with the brush provided and reapply an even layer

Frequencies: 71Hz, 89Hz, 139Hz, 184Hz, 284Hz, 355Hz, 535Hz, 630Hz (And others possible if searched for) Updated on: 06/19/13