Is there a difference between a black light and a UV light?
Answers
Explanation:
The difference in the light itself is just the different frequencies, the different wavelength associated with the different frequencies and finally, the different energy per photon that results when the frequencies are different. The other two, however are immediately defined as soon as the frequency is given. So all are the same electromagnetic effect at slightly different frequencies. However, different materials react differently to the different frequencies with a wide range of responses, but the cause here is largely in the materials and systems, such as living things vesus not living things, The light itself is pretty much the same but in the frequency region near where “light” becomes visible light is also beginning to carry enough energy in each photon to excite atomic and molecular responses.
Just to give an example, we think of radio transmissions at 200 kHz or 900 MHz all as pretty much the same effect, though the ratio of frequencies represented is quite wide (factor 4500) compared to the ratio in IR to UV frequencies to which we are commonly exposed and pay attention to (the range I give for radio is crudely what we receive as radio or TV broadcasting). A major important reason is that in the IR to UV range we start to have energies able to affect materials, molecules and so on which are extremely important to our lives (bodily functions, food production, injury by UV, etc.), we we start to think of the cause as a change in the light although that change is fundamentally relatively small, It is the atoms being hit by the light which make the big differences in effects.
Incidentally, black light is just a street name often used to mean the same thing as ultraviolet light.