The "sound of water" is a silent video representing water movement at different frequencies! A hose is attached to the speaker with tape, such that when the speaker produces sound, it will vibrate the hose with the same frequency. Three different frequencies were captured at constant amplitude using a tunable speaker. The effect cannot be seen with the naked eye and only works through the camera with minimum 24 frame per second. For the frequency of 23 Hz, the water has shown to move backward!!! We set the frame per second to 24 which is greater than the actual frequency of water! Therefore, illusion happens and your eyes think the water is moving backward! For the fluorescent dye movies, Rhodamine B Fluorescent dye was used in laser green light!
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