Light and a Water Droplet
Part of the light falling on this water drop enters and is reflected from the back of the drop. This light is refracted and dispersed both as it enters and as it leaves the drop.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, Dispersion: The Rainbow and Prisms. January 13, 2013."
http://cnx.org/content/m42466/latest/
OpenStax CNX
CC BY 3.0.