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What instrument (uv meter) would I need to measure the results?
These ultra-low cost beads are extremely sensitive to natural light and change colour dramatically from white to various colours when taken outside - even on an overcast day. Containing trace amounts of a photochromic pigment that responds the the ultraviolet component of daylight, the beads have many different uses ranging from scientific testing of (UV) sun block materials to the creation of 'smart' jewellery.
Allan Rogerson asked the Naked Scientists: My son is wanting to test amount of UV light emitted from the cfl lightsfor his science project. What instrument (uv meter) would I need tomeasure the results?Thanks for your help.Allan RogersonWhat do you think?
To put the amount of UV emitted from fluorescent lighting in context a 1993 study found that UV exposure from sitting under typical office fluorescent lights for eight continuous hours is equivalent to just over one minute of sun exposure (Lytle et al, 1993).
Spectra from another website which seems to confirm the violet line is actually UV (~400nm)...[attachment=6500]http://ioannis.virtualcomposer2000.com/spectroscope/amici.html#1fluopAccording to this site 436nm is "the approximate limit of human vision at shorter wavelengths, i.e. a 400nm line would not be visible to the human eye.
I can see the 405nm line. It is visible and therefore it is not UV.
Only near UV is of interest for UV photography, for several reasons. Ordinary air is opaque to wavelengths below about 200 nm, and lens glass is opaque below about 180nm. UV photographers subdivide the near UV into:Long wave UV that extends from 320 to 400 nm, also called UV-A, Medium wave UV that extends from 280 to 320 nm, also called UV-B, Short wave UV that extends from 200 to 280 nm, also called UV-C. (These terms should not be confused with the parts of the radio spectrum with similar names.)
[attachment=6498]http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/colours-in-cds/I suspect the violet line in this spectrum is caused by UV and was not visible to the eye but has been recorded by the camera as a false violet colour. Cameras, film & digital, can "see" UV, human eyes cannot
I can confirm that the second purple line which Dave has marked "UV?" and must be the 405nm is barely visible (but just discernable if I look for it and catch a bright reflection of the light) using a DVD and simple setup.
I can see the 405 nm line, but I can't see the link between this stuff about IR and the original question.