Does a blacklight have more uv than a 100watt incandescent bulb?

Question

I'm doing a science project to test the strength of sunblock spf by using beads that react to uv rays(change color). Instead of sunlight I need to know whether a blacklight or a 100 watt bulb has more uv. any other tips for the project would be great too. thanks =)

Answer 1

If you use a fluorescent blacklight tube, it has much more UV than an incandescent bulb (and would be much better for your experiment).  you can buy incandescent blacklight bulbs, which are just normal bulbs with a UV pass filter on them and they don't work very well.  

Do you think it might be hard to get the sunscreen on the UV beads?  Also, remember that sunscreen is protecting from higher energy UVA and UVB  rays.  Most of the UV in blacklights is in the safer low-energy-near-visible UV--you don't usually get a suntan under them.  You might consider the fluorescent bulbs for tanning beds?  There are also small, handheld UV units for geology that use higher energy UV.  Also, some halogen lights let out a lot of the higher-energy UV and require a special glass screen for safety.  Anything that you buy for consumer use will have very low UV that is below the range that is targeted by sunscreen.  If you remove any of the protective filters from consumer products (like the glass from a halogen work light), you may endanger yourself, so be very careful!

Also consider that many sunglasses and lab goggles are supposed to block high-energy UV rays and may be good for an experiment (and good for you to wear while performing such an experiment)