Why does a half full wine glass make a sound if i rub my fingers on the top?

Question

is there a specific word ?

Answer 1

This is a pattern called "resonance". Resonance is when one object vibrates with a certain frequency, and another object that has that fundamental frequency (ill explain below) will vibrate too. So, given the right conditions (including depth between wine and rim, type of glass, etc.), the glass will vibrate with the same frequency that your finger is generating.

This causes an effect known in physics as an "open-ended sound column", which will generate louder sounds when there is a certain amount of space between the top and the bottom (wine).

Everything has a "fundamental frequency". It's the frequency that it vibrates at under normal conditions (see Kinetic Molecular Theory for more info on "everything vibrating").

A very, very, very cool example of resonance on a large scale is the Tacoma Gorge bridge - search google or YouTube for it.

Answer 2

Two things are going and most of the other answers only point to one.
When you drag your dampened finger along the rim of the glass, it catches then releases repeatedly (if it is too wet, too dry, or soapy, it won't catch and no sound) which sets up vibrations in the glass. If you rub at just the right speed, your vibrations match the resonant frequency of the glass and the whole thing starts vibrating. While lead glass, which is denser, usually makes a nice sound, usually because the glass is thin, any glass which rings when tapped lightly will sing on the same note, and I have had drinking glasses and Pyrex glassware that will do it. Adding water or wine adjusts the frequency of the column.
Ben Franklin invented a musical instrument consisting of nested glass bowls revolving on a shaft that was played by touching the rims with a wet finger. He called it a Glass Harmonica. Modern versions are made of Pyrex because of concerns of constantly rubbing the skin on the lead glass used previously. http://www.glassarmonica.com/index.php
click for samples

Answer 3

that word is vibrations..it will make a sound even if the glass is empty..plus it needs to be a lead crystal glass.
as you run your finger around the rim it will cause the glass to vibrate then the shape of the glass acts like a speaker and directs the sounds outwards.

Answer 4

it has to be lead crystyl
it vibsates and the sound waves make sounds
try same glasses filled uo to different levels

Answer 5

if you look close at the liquid in the glass the audible frequency is visible as waves on the surface if the liquid.