Hi, I’m Tech Adams
Today, I wanted to show you this. To the naked eye and to the camera,
this piece of glass appears clear, but it’s not. Oohh, see how clear. In order to show that it’s
not clear, I need three things. A black piece of card,
a yellow highlighter, and an ultraviolet flashlight. The ultraviolet flashlight emits light primarily in the
ultraviolet spectrum, along with a little bit of visible
violet and blue light. The yellow highlighter contains
special pigments called phosphors, that react to ultraviolet
light and glow. When I put this piece of glass
between the source of ultraviolet light and the yellow phosphors,
the glow disappears. That’s because this is an ultraviolet filter,
it’s designed in such a way that the ultraviolet wavelengths
are absorbed while allowing all visible light to pass through. Glow, no glow, glow, no glow. Since the phosphors are glowing
in the visible range, putting the UV filter between the color and the
camera does absolutely nothing. While this particular filter
is used to remove ultraviolet light for cameras, similar ultraviolet
filters are used in sunglasses to protect the eye.
Nearly all sunglasses provide UVA and UVB protection
in part because of the overall darkening of the lens. Some eyeglasses have a UV coating. Some don’t. Don’t forget to like, subscribe, and share this video with your friends so that
they too can see the magic of the ultraviolet filter.
For Tech Laboratories, I’m Tech Adams, Saying “Keep Thinking” and
thanks for watching.