The color of soap bubbles
Where does the color of the bubbles come from?
This page is based on the basic page The color of soap bubbles. So if you have not read it yet, it might be a good idea to start with the link to the right :)
Light will be polarized when reflected in a soap film in the right angle. Light coming directly from the sun is not polarised. This means that the waves occilates in all directions perpendicular to the direction of propagation. This is often symbolised as:
Unpolarized light
On the other hand, when light is fully linearly polarised it will only consist of waves moving in one plane as illustrated:
Polarized light
That light can be polarized by a soap bubble can be shown by a simple experiment. A black area appears when holding a polarization filter between the soap bubble and the camera.
The linear polarisation filter cause a dark area in the top right corner of the bubble
The polarisation filter is turned 90 degrees so that the dark area is now in the top left corner
If the bubble did not polarize the reflected light, the bubble would appear homogeneously bright. The two photos above show that there here are areas at the bubble from which only polarized light is reflected towards the camera.
