Uploaded January 2025 | Updated September 2026, 1 week ago

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A piece of fleece generates sound just projecting a modulated light! No electronics involved! (Aside the light modulator.)

*This plays sound JUST with light!*

I reproduced an experiment that led to the definition of the photoacoustic effect. This effect has been first discovered by Alexander Graham Bell, the inventor of the telephone and of the photophone. While this effect is widely exploited in photoacoustic spectroscopy, it is often overlooked by many.
So with this video I bring it to light ...so to say :-)
After a first failure in reproducing the experiment, after some research I managed to achieve results.
Encouraged, I developed a special #LED driver. The final result is amazing: a simple piece of fleece emits #music just for the radiated modulated light!

The effect is regarded to be caused by light induced thermal expansion and contraction of materials.

In doing this experiment I also stumbled upon a weird response from a piezoelectric sensor, with an unexpected and interesting effect that I showcased in a bonus extra section of the video.

Remark: This video has been redone because of missing content and technical issues in the originally posted video.

Full series of #Experiments: youtube.com/playlist?list=PLwbCeSU2Kq_wbNEUGGWLkCgvLpUz3eP-k
Full series of #Electronics: youtube.com/playlist?list=PLwbCeSU2Kq_zORt4un2iQ3JUYxzWF3cTJ

Visit the website: accidentalscience.com