Uncovering Resonance Frequency in Wine Glasses

[LachlanMc]

Hey guys,

Homework Statement

I am conducting an investigation in which we will be playing around with the resonance of different wine glasses. I would like to know what characteristics of wine glasses cause the resonate frequency to change. Preferably not a direct answer but more a hint of what to investigate or how to find it. I have been researching it within other structures such as open and closed tubes as well as string. This makes it easier to assume its going to a variable such as the circumference or depth but this cannot be hypothesized until investigation is done. So any help put forward is much appreciated.

Regards,
Lachlan

 

[LowlyPion]

Welcome to PF.

I'd suspect that the circumference of the top is pretty important.

Along these lines this lecture touches on the subject about 34:10 in.

https://www.youtube.com/watch?v=q4setd7BZWM

 

[LachlanMc]

Thanks for the kind welcoming LowlyPion, also thanks for the video it is very relevant to what I am doing. Can you provide any more information on the subject as I am still unable to construct a hypothesis. This is on exactly what characteristics of the glass will change the resonance in which way (pitch...ect).

 

[Carid]

Just off the top of my head, I'd say we should look at some objects which are well known for their resonant properties and then try to relate that to the question of the glass.
A bronze bell or a violin string are excellent resonators. One has a hard material which has a restorative force when whacked by a clapper, the other is a soft material under tension which thus exerts a restorative force. If I replace bronze with aluminium, or catgut with string I will notice some difference in the resonance. So the type of material is important.
If I compare a smaller bell with a larger, or I shorten a violin string with my finger, the pitch is found to be higher, so the characteristic length vibrating is important.
Similarly,f I make the bell or the violin string ten times thicker we may find we have less resonance. So thickness is a factor.
Then comes shape. If the bell was of uneven thickness or irregular shape, or if the violin string was significantly thicker at one end than the other, then resonance would be much less in evidence, so we can say the shape should be regular, that it should exhibit symmetry. Cow bells are more or less rectangular and don't sound at all like round ones.
A glass can exhibit properties of resonance which vary with the material, characteristic length, thickness, shape, and symmetry, plus you might want to put some liquid in it and that'll also affect the resonance.