Seth Paternostro

"Flourescent Fun"

A burning orange glow, like that of molten iron, dips into a blue liquid-filled jar as flame-like tendrils reach down into the depths. While heated metal would seem like an exciting explanation, the only materials used to produce this were a glass jar, a long matchstick, water, some fluorescent paint, and a black light. The bright orange colors that make this photo interesting are produced through a phenomenon called fluorescence.

As invisible ultraviolet light illuminates the paint, excited electrons return to lower energy levels in a couple of small steps. At each step that the electrons move to, photons of lower energy and visible wavelengths are produced, leading to the characteristic glow. The paint on the surface of the water is held there by surface tension, which seems to create an almost membrane-like layer. However, with the help of gravity, the paint particles slowly make their way into the water, like flames grasping for the bottom of the jar. This is known as diffusion, since the paint particles are moving from an area of high concentration at the top of the water to an area of low concentration throughout it.

Two other exciting physics concepts are illustrated in the image: reflection and refraction. The darker orange line that forms a cross with the matchstick is just a reflection, or an absorption and re-emission of light, on the back of the glass, while refraction is seen along the matchstick as the light changes direction in the water.

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