UV Beads

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uv beads

Ultraviolet (UV) sensitive plastic beads are generally white but turn colors when exposed to UV light. In particular, the beads have color when exposed to light of wavelengths between 360 to 300 nanometers, in the UV-B range. 

Students are given pipe-cleaners and a variety of beads, including UV beads, as well as a UV flashlight in order to see what colors their bracelet will turn when exposed to the UV in the sun's rays.

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types of em radiation

This activity introduces students to the concept of forms of light that we cannot see. One example of this, UV light, cannot be detected by our eyes but is emitted by the sun and other starts. This is a great chance to talk about applications of UV light. We are exposed to it on a daily basis through the sun, but we also use it regularly in the laboratory in order to make chemical reactions happen!

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glowinthedark

We also can bring glow-in-the dark beads and introduce students to words that describe transitions between electron energy states such as fluorescence and phosphorescence. Some beads fluoresce, meaning they absorb light and immediately emit light of a longer wavelength / lower energy only while the light source they are absorbing from is on. Other beads phosphoresce, meaning they absorb light and then emit the even longer wavelength / lower energy light over a longer period of time even after the light source they absorb energy from has been removed. This is how glow-in-the-dark toys like stars, stickers, and these beads are able to glow even in a pitch-black room!

Teachers can build on the UV bead bracelet-making activity by having students bring their bracelets back to the classroom and conducting experiments with them. Have students make predictions about what scenarios will prevent the beads from changing color by shielding them from UV light. Are they safe under water? What about under a cloth? How about sunglasses? Test their theories and have them record their results. NASA and the Stanford Solar Center have collaborated for a great lesson on UV using these beads.

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beads