 |
 |
The Mystery Window
How to use the exhibit:
- Turn on the light source that is located just behind the Mystery Window.
- Observe the red glow of the light that comes through the window, when the “Red” side is toward you.
- Note that the Mystery Window is on a rotational pivot and that there is a counter weight on the bottom to keep the red side toward you.
- Rotate the Mystery Window so that the “Blue” side is now facing you. You will need to hold onto the window in this position due to its counterweight.
- Note that hardly any light comes through, only a very small amount of blue light is visible!!
- Why is the Mystery Window not reversible?
How Come?
This window consists of three layers of plastic: one tinted deep blue, one with a red fluorescing tint, and the one with a deep red tint in that order. The mystery is solved if one understands the phenomenon of fluorescence:
- Light come in “energy packets” called photons. The energy in the photon depends on the color of the light or wavelength: blue photons have higher energy then red photons.
- When the blue film is toward the light source, a blue photon strikes a molecule of the fluorescent material , the photon energy is absorbed by the molecule, the molecule is then in an exited state.
- The molecule then emits light in order to lower its energy, the emitted photon has an energy lower than the incident one – i.e red photons are emitted and pass thru the red filter.
- When the red film is toward the light source, the red light passes thru the fluorescent film, but is absorbed by the blue filter, almost no light comes thru.
Fluorescence can turn blue light into red light but not vice versa.
Light come in “energy packets” called photons. The energy in the photon depends on the color of the light or wavelength: blue photons have higher energy then red photons.
When the blue film is toward the light source, a blue photon strikes a molecule of the
Fluorescent materials absorb photonic energy then re-emitted photonic energy at a lower energy level.
by the molecule, the molecule is then in an exited state.
The molecule then emits light in order to lower its energy, the emitted photon has an energy lower than the incident one – i.e red photons are emitted and pass thru the red filter.
When the red film is toward the light source, the red light passes thru the fluorescent film, but is absorbed by the blue filter, almost no light comes thru.