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daniel_i_l
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Why does black light (florecent light without the coating) light up only white things?
Um, if that were true, the object would only emit UV. In fact, it is emitting a different wavelength than that which it is absorbing.moose said:I believe what you are asking is the same type of question as:
"Why does red light only light up red and white things?"
I think it's the same answer too ;)
Yes, but read thisDaveC426913 said:Um, if that were true, the object would only emit UV. In fact, it is emitting a different wavelength than that which it is absorbing.
howstuffworks said:UV light waves are too short for us to see -- they are completely invisible -- so fluorescent lamps have to convert this energy into visible light. They do this with a phosphor coating around the outside of the tube.
Phosphors are substances that give off light -- or fluoresce -- when they are exposed to light. When a photon hits a phosphor atom, one of the phosphor's electrons jumps to a higher energy level, causing the atom to vibrate and create heat. When the electron falls back to its normal level, it releases energy in the form of another photon. This photon has less energy than the original photon, because some energy was lost as heat. In a fluorescent lamp, the emitted light is in the visible spectrum
Black light, also known as ultraviolet light, is a type of electromagnetic radiation that is invisible to the human eye. It has a shorter wavelength than visible light, allowing it to penetrate certain materials. When it comes into contact with certain materials, it can cause them to emit visible light, making them appear to glow.
White objects appear to glow under black light because they contain fluorescent compounds that absorb the UV light and emit visible light. These compounds, known as phosphors, are commonly found in laundry detergents and highlighters. The absorbed UV light is then re-emitted at a longer wavelength, making it visible to the human eye.
No, not all white objects will glow under black light. Only materials that contain fluorescent compounds will glow, such as certain fabrics, paper, and plastics. Other materials, such as metals and natural materials like wood, will not glow because they do not contain these compounds.
The intensity of the glow of white objects under black light can vary due to a number of factors. The amount of fluorescent compounds in the material, the distance from the light source, and the strength of the UV light can all affect the intensity of the glow. Additionally, the age and quality of the material can also play a role.
In most cases, black light is not harmful to white objects. However, prolonged exposure to strong UV light can cause fading or discoloration of certain materials. It is important to use black light responsibly and avoid shining it directly on sensitive materials for extended periods of time.