Here’s What You Need
- UV beads (you can find them at Steve Spangler Science, Arbor Scientific, or other online science supply vendors)
- Plastic or leather cord
- Sun screen (optional)
- Plastic sandwich bags (optional)
- Permanent marker (optional)
Do the first part of the activity inside and away from any sunlight (e.g. stay away from windows). Take the white UV beads out of the bag and expose them to light in your home. Most of the light inside our homes is fluorescent or incandescent light…not UV. Did your beads change in any way?
Now, take your beads outside and expose them to the sun. Do you notice anything? The white UV beads will change color depending on the pigment in the bead. The color change is not permanent. When you head back inside and away from the sunlight, the beads will become white again. In fact, the beads will change color about 50,000 times before they stop responding to UV light!
You can use the plastic or leather cord to create a necklace or bracelet of UV beads. Now, you will have a way to quickly detect UV light and remind you to wear your sunscreen. Jewelry the practical, fun, and educational…you have to love that!
You can also use the UV beads to test different brands of sunscreen. If you’re like me, you probably have a few different brands hanging out under the bathroom sink. Try to find some with different Sun Protection Factors (SPF) ratings. Now, grab your plastic sandwich bags. You will need one bag for each of the sunscreens you want to test. You will also need an extra bag to use as a control (something to compare to your other bags). While inside, place some UV beads in each of the bags. Rub a different sunscreen on the outside of each of the bags. Use the permanent marker to label each bag. Make sure you also prepare a bag of beads with no sunscreen on the bag. Now, it is time to experiment!
Take your sunscreen-covered bags and your no-sunscreen bag outside and lay them in them on the ground in the sun. Do you notice any difference between the bags? Are the colors darker in some bags? Make a note of which bags have the darkest colors. You might notice a connection between the color of the beads and SPF rating on the sunscreen. Sunscreens with a higher SPF rating block more UV light energy. The beads in these bags should be lighter than those in the other bags. Of course, all the beads should be lighter than those in the unprotected bag. It just goes to show that some sunscreen is better than no sunscreen at all.
Note: You can also use this experiment to test different bands of sunscreen. However, if you want to test different brands make sure they all have the same SPF rating.
The Science Behind the Beads
The UV beads used in this activity were created using a special pigment that responds to UV light energy. UV light cannot be detected with our eyes. In fact, our eyes can only detect a certain type of light energy called visible light. Other animals, however, can see UV light. For example: Butterflies can use ultraviolet markers to select a mate. Reindeer rely on ultraviolet light to find the lichen they like to eat. Bees use UV light to hone in on UV markings of certain flowers like the Black-eyed Susan. While we cannot see UV light, it is there whenever the sun is in the sky. That includes cloudy days, rainy days, and winter days!
Just like visible light, there are different types of ultraviolet light. Short wave ultraviolet light is used to identify fluorescent rocks and kill bacteria. You are probably more familiar with long wave ultraviolet light. In fact, you have probably used them in your home around Halloween. That’s right. Long wave ultraviolet light is the type of light that is created by black lights (those cool lights that make your clothes and decorations glow)!
Many people love to play in the sunshine. However, when your skin is exposed to sunlight for extended periods of time it changes. The UV light energy can beak the chemical bonds in your skin causing it to wrinkle and lose flexibility. Too much of this type of exposure can also lead to skin cancer. Sunscreens are designed to block UV light. They act as a barrier between the dangerous and invisible UV light and your skin. As a result, it is important to select the right sunscreen and reapply it continuously if you are going to be spending a lot of time outside. There you have it; some of the science behind UV light. Have fun in the sun this summer, wear your UV bead bracelet, and use your sunscreen!