As James said, it is resonance. When you rub your finger around the rim, the friction causes vibration. This vibration occurs at a certain speed, or frequency and we hear it as a certain note. If you change the level of water in the glass, it will change the frequency and sound different.
Do you mean the trick where the glass rim is rubbed with a wet finger? This is caused by resonance but I don’t know more than that. Sorry 🙂
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Hi Shaunt,
As James said, it is resonance. When you rub your finger around the rim, the friction causes vibration. This vibration occurs at a certain speed, or frequency and we hear it as a certain note. If you change the level of water in the glass, it will change the frequency and sound different.
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Nicely explained, Dustin.
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