# PHY C15: Stationary Waves in Strings/Air Columns

Today, we’re covering:

• Stationary waves in strings
• Stationary Waves in tubes
• Harmonics & Overtones

Now, we will consider stationary waves formed in columns of certain lengths.

We will mainly focus on 2 examples:

Here, we will consider both examples as being a COLUMN (a length where the wave can form).

Features of a column:

What affects the formation of stationary waves?

Why do these factors determine whether a stationary wave will be formed?

TYPE OF COLUMN

To form a stationary wave, you need to fulfil 2 simple requirements:

• The CLOSED end(s) of the column must coincide with a NODE of the stationary wave
• The OPEN end of the column must coincide with an ANTINODE of the stationary wave

Thus,
The LENGTH (L) of the column must be able to accommodate these requirements in order for a stationary wave to be formed.

As you can see,

• the distance between a node & a consecutive antinode is always λ/4
• the distance between a node & a consecutive node is always λ/2

With this, we can conclude:

This way, you can find the frequencies where a stationary wave can form, given a way to get the values of L, v & n.

What is the lowest allowed frequency for a stationary wave called?
The FUNDAMENTAL FREQUENCY.
This is when n = 1.

What are the allowed frequencies for stationary waves called?
HARMONICS or OVERTONES.
There is a difference in usage:

Solving problems involving harmonics:
There is a simple way to deal with these problems!

Next, we’ll see how to measure the speed of sound experimentally using stationary waves.

⇐ Previous in Physics: Stationary Waves (Intro)
⇒ Next in Physics: Measuring the speed of sound using stationary waves

## 3 thoughts on “PHY C15: Stationary Waves in Strings/Air Columns”

1. Pingback: 15. Superposition – ProDuckThieves