Science Buddies: "Ask an Expert"

There a so many uv lights!? I need to imitate exposure to the sun. Do I need short wave or long wave?

Need to start this week so I need to get my light source ordered ASAP.

I will be exposing a bacteria to test UV protection of fabrics.

Hi!

I'm not entirely sure, but I think you should use long wave UV radiation. That is because 99% of the radiation from the sun comes from UVA or long wave UV (380-315nm). Look at this site for more info:

http://en.wikipedia.org/wiki/UV

Also, be sure to buy UV protection goggles or sunglasses! Be cool!

Hi,

Check out the following link - explanations a lot about UV light and the sun:

http://en.wikipedia.org/wiki/Ultraviolet

You could start by using UV-A (long wave). Or you could use both short or long wave individually - some UV lamps have both wavelengths. You could compare which wavelength works better in your experiment. It depends what kind of UV lamp you have access to.

Possible sources for UV lamps:
First ask your science teacher if there is one available at your school. There are various science supply companies your teacher may be familiar with also.
Or you could try the following link:
http://www.uvp.com/new/

Remember to be very careful when using UV lamps.

Hope this helps!

Mary

Hi there,

I agree with Mary and Jessica, but wanted to add some additional information. When you read the wikipedia website, it becomes clear that there are a range of wavelengths in the UV range. The middle range (UVB) and some shorter wavelengths of UVA are associated with skin cancer, and very shortwave UV (UVC) is germicidal (kills microbes).

Because you're testing different types of fabrics for UV protection, I wasn't sure if you were more interested in the skin protectant aspect versus bacteria-killing aspect.

If you're confused about the difference, this webpage may answer some more questions. Pay close attention to the portion talking about which ranges of UVA are associated with skin cancer.

http://www.telemedicine.org/sundam/sundam2.4.2.html

In any case, it seems as though which wavelength you choose depends on whether you're more interested in the germicidal or skin-damaging wavelengths. I like Mary's suggestion of testing both if possible.

In addition to checking with your teacher, local universities and companies are also a great resource. Short and long-wave UV-illuminated boxes are standard tools for anyone who works with DNA, so you may try calling a local university/company to see if you can gain access to perform your experiments. If you need any help with this aspect, please ask.

And as all the experts have been saying, please be careful! Make sure to wear goggles and skin protection when you're working with UV light.

Best of luck,
Linh