Standing waves can happen in air, especially when sound waves bounce off fixed surfaces. This is really interesting and useful in many areas, like music and sound design.

How Standing Waves Form

1. What Happens When Waves Bounce: When a sound wave travels through the air and hits a fixed boundary, like the end of a tube or a wall, it bounces back. This bounce allows the original wave and the new reflected wave to add together.

2. Nodes and Antinodes:

   • Nodes: These are points where the waves meet and cancel each other out. At nodes, there is no movement in the medium, like the air.
   • Antinodes: These points show where the waves add together really well, causing a lot of movement in the medium. Here, the sound wave is the strongest.

Example: A Pipe Organ

Think about a pipe organ. Inside the pipes, the air column is the medium. When a sound wave is made at one end, it reflects off the closed end of the pipe. This creates standing waves. Depending on how long the pipe is, different patterns of nodes and antinodes can appear.

Simple Formula

We can show the link between the length of the air column and the wavelengths of the standing waves like this:

$L = n \frac{\lambda}{2}$

• Here, $L$ is the length of the pipe.
• $n$ is a whole number (which we call the harmonic number).
• $\lambda$ is the wavelength.

To sum it up, fixed boundaries play an important role in creating standing waves in air. By learning about nodes and antinodes, we can better understand how sound works in different spaces.