Why does an opera singer's voice break glass?

An opera singer's voice can break glass due to a phenomenon called resonance, where the glass vibrates at its natural frequency.

Resonance is a fundamental concept in physics, referring to the phenomenon where an object vibrates at its natural frequency when exposed to a similar frequency. In the case of an opera singer breaking glass, the singer's voice produces sound waves that match the natural frequency of the glass. This causes the glass to vibrate, and if the amplitude of the vibration is large enough, the glass can shatter.

The natural frequency of an object is determined by its physical properties, such as its size, shape, and the material it's made from. For a piece of glass, this frequency is typically in the range of human hearing, which is why an opera singer can potentially break it with their voice. However, it's not as simple as just singing any note. The singer must produce a note that matches the natural frequency of the glass exactly, and they must sing it loudly enough to generate a large amplitude of vibration.

Furthermore, the singer must sustain the note for a certain period of time. This is because the energy from the sound waves is transferred to the glass gradually. If the singer stops singing too soon, the glass won't have absorbed enough energy to break. This is why you often see opera singers holding a high note when they're trying to break a glass.

In conclusion, an opera singer's voice can break glass due to the physics principle of resonance. By singing a note that matches the natural frequency of the glass, and sustaining it long enough, the singer can cause the glass to vibrate with a large enough amplitude to shatter. This is a fascinating demonstration of the power of sound and the delicate balance of forces in the physical world.