Wine glasses exhibit four nodes at the 4th harmonic due to their circular shape, which inherently supports multiple oscillation modes. The fundamental frequency of a wine glass remains constant regardless of water level; however, the effective oscillation changes as the glass must move more water, requiring more time for the same displacement. This results in a complex interaction between the glass and the liquid, affecting the perceived sound. The primary oscillation mode involves compression in one direction and expansion in another, leading to the formation of four nodes and four anti-nodes.
PREREQUISITESPhysicists, acoustics researchers, and anyone interested in the science of sound production in glassware and musical instruments.
If the glass has to move more water in the oscillation, it needs more time for the same displacement (at the same elongation => same force).and also does the fundamental frequency of the object (wine glass + water) change when water level is changed.