# B What is the concept of Physics of Cymatics (of a liquid)

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1. Sep 6, 2016

### Rosella Lin

Hi,

Could someone please help me about what is the physics concept behind Cymatics. Is there a formula which establishes the patterns form on a liquid when the frequency or amplitude are changed?

Thanks.

2. Sep 6, 2016

### Staff: Mentor

Are you familiar with the basics of waves and resonances? The wikipedia article is a good starting point:

https://en.wikipedia.org/wiki/Cymatics

3. Sep 6, 2016

### Rosella Lin

Yes I have studied waves and resonances but I don't understand what is going on with the patterns of the cymatics

4. Sep 6, 2016

### Staff: Mentor

It's just a way to make the modes of resonance visible. Like when you put sand on a vibrating metal plate...

5. Sep 6, 2016

### Rosella Lin

ok i see. But is there no formula or pattern it follows?

6. Sep 6, 2016

### Staff: Mentor

For the simpler patterns, you can generally write the equations that show what the pattern will be, given the shape of the surface, how it is suspended/held, and the driven locations and frequencies. For the more complex patterns, you could probably simulate them, but if there are good mathematical solutions, they are likely to be complicated (like, beyond what I can try to help you with).

Nice web page with tutorials and cool videos/pictures -- http://doorofperception.com/2013/11/cymatics/

7. Sep 6, 2016

### Staff: Mentor

Mathematically, these problems are solved using Boundary Value methods:

https://math.dartmouth.edu/archive/m23f09/public_html/drum.pdf

and here:

https://en.wikipedia.org/wiki/Boundary_value_problem

Basically you define how the edges of the boundary, use the 2D wave equation and through the magic of partial differential equations come up with a family of functions that solve it.

As an example, a drum head has a non-moving circular boundary and so it limits the kinds of waves known as standing waves that can occur:

https://en.wikipedia.org/wiki/Vibrations_of_a_circular_membrane

From there you can determine nodal lines ie where the head doesn't move and that's where the sand on the drum surface will tend to sit.