A wine glass filled with water (approximately half or a quarter), when you use a wet finger and rub the top of the wine glass, the wine glass will produce a sound. I heard that it is because of the "stick and rub" effect ... Can you explain this effect or other principal that cause this sound to be produced? how much water is least needed to produce a sound? What and why is the relationship between the quantity of the water and the pitch of the sound? Will the sound produced be greater if we use a denser or less dense liquid than water? Thx for explaining :D

  • $\begingroup$ I like to learn more about the relationship between the material, shape, size and how that all affect the vibration. What subject should I be looking into? $\endgroup$
    – sooon
    Sep 9, 2014 at 2:30
  • $\begingroup$ Related: physics.stackexchange.com/q/247516/63055 $\endgroup$
    – pentane
    Jan 6, 2018 at 20:35
  • $\begingroup$ @RedGrittyBrick That link seems to be dead $\endgroup$
    – usernumber
    Jan 10, 2020 at 9:37

1 Answer 1


Vibrations begin to resonate together into sound waves we can hear. We can make the sounds loud or soft depending on how much pressure we place on finger. The pitch of the sound can also be changed by adjusting the amount of water in the glass.As you rub your finger on the rim, your finger first sticks to the glass and then slides. This stick and slide action occurs in very short lengths and produces a vibration inside the glass which, in turn,produces a sound. Vinegar helps to clean dirt and oil from your finger. A clean finger improves the stick and slide action. As soon as the first few vibrations are produced, the glass resonates. That means you’re causing the crystals in the glass to vibrate together and create one clear tone. You can change the pitch (highness or lowness of the sound) by adding to or subtracting from the amount of water in the glass. The volume (loud or quiet) can be changed only a little bit by increasing or decreasing the pressure from your finger.


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