# Pressure standing wave nodes at the end of the open side of

• crick
In summary, standing sound waves can be formed in a one-side or two-side open tube due to the reflection of the wave at the open end. The pressure at the open end must be fixed to atmospheric pressure, creating a node of pressure that traps the sound wave in the tube. However, in instruments like a clarinet, the sound wave is able to exit and propagate from the tube. The reason for the pressure wave nodes at the open end of a tube is explained in detail in the provided resources.
crick
I do not understand why standing sound waves can be formed in a one-side or two-side open tube. Consider a one-side open tube.

In particular how does the reflection of the wave at the open end occur? I found the following explanation.

The sound wave is a pressure wave and at the open end of the tube the pressure must be fixed to the atmosferic pressure and cannot vary, thus there is a node of pressure there.

I do not get why the pressure at the open end cannot vary from the atmospheric pressure.

Furthermore, if the outside pressure does not change, the sound wave (a pressure wave) is somehow trapped in the tube and do not exit from it. Nevertheless for example in a clarinet the sound wave do exit and propagate from the tube, I guess. Otherwise how could the sound be heard?

What is the reason why there must be pressure waves nodes at the open end of a tube? (As in picture, in (b))

## 1. What is a pressure standing wave node at the end of the open side?

A pressure standing wave node at the end of the open side is a point where the amplitude of a standing wave is zero and the pressure is at its maximum. This occurs at the open end of a tube or cavity when a standing wave is formed due to the reflection of waves at the closed end.

## 2. How is a pressure standing wave node different from a displacement standing wave node?

A pressure standing wave node is different from a displacement standing wave node in that the former is a point of maximum pressure while the latter is a point of zero displacement. In other words, at a pressure standing wave node, the air molecules are not moving while at a displacement standing wave node, the air molecules are at their maximum displacement.

## 3. What causes the formation of pressure standing wave nodes at the end of the open side?

Pressure standing wave nodes at the end of the open side are formed due to the interference of waves. When a wave is reflected off of a closed end, it combines with the original wave to form a standing wave. At the open end, the reflected waves interfere destructively with the original wave, resulting in a node of zero pressure.

## 4. How do pressure standing wave nodes affect the sound produced in an instrument?

Pressure standing wave nodes play a crucial role in the sound produced by an instrument. They determine the resonance frequencies of the instrument and affect the quality and tone of the sound. By adjusting the length of the instrument, one can change the location of the pressure standing wave nodes and therefore alter the sound produced.

## 5. Can pressure standing wave nodes occur in other mediums besides air?

Yes, pressure standing wave nodes can occur in other mediums besides air. They can occur in any medium where waves can propagate, such as water or solids. In fact, they are the basis for various types of musical instruments, such as string instruments and drums, where standing waves are formed along the length of the instrument to produce sound.

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