You may have seen in cartoons and advertisements how an open singer’s voice shatters glassware into pieces. But it is actually possible? Yes, provided it is loud enough to satisfy certain science principles.
When sound hits an object – such as a glass tumbler – it excites the particles inside, causing the tumbler to vibrate. Each object will naturally vibrate at a particular frequency – known as its resonant frequency is the natural frequency. In other words, resonant frequency is the natural frequency at which an object vibrates if disturbed by some stimulus, such as a sound wave. So, to shatter the glass, the soundwave should match that frequency, or pitch. In that frequency, the object will start to shake and eventually shatter.
How loud are we talking about? According to scientists, the singer has to be very loud – an intensity of at least 105 decibels. But no matter how loud the sound, if the pitch doesn’t match the resonant frequency of the glass, the glass will reflect most of the energy and won’t break. So, one should identify the resonant frequency of the glass, before trying to tap it.
Mind you, not every glass will break this way. The glass must have microscopic defects and it should be thin. Crystal glasses with nearly vertical sides are the best, scientists recommend.
Microscopic defects will make the glass buckle under pressure.
Glasses with narrow stems are especially resonant because of their hollow shape which allows the vibrations to be held without dampening them down.
Picture Credit : Google