How the UV Beads work....

• Ultraviolet (UV) light is one of the invisible frequencies of light that is given off by the sun and is divided into 3 bands: UVA,UVB, and UVC. Moderate UVB light causes the skin to produce  vitamin D. However, both UVA and UVB destroy VItamin A in the skin. UV light, especially UVC, can destroy many types of mold, viruses and bacteria and is used to pasteurize fruit juices. Over exposure to UV light can be very harmful to many things, including humans! Some of the effects can be seen in sunburned skin, faded paper, or a cracked rubber hose that has been left in the sun.
• UV-sensitive Beads contain a pigment that changes color when exposed to UV light from the sun or other UV sources. They are not affected by visible light and so will remain white when indoors or shielded from the sun.

Other fun activities:

1. Apply sunscreen to the beads to test how much it will filter the UV light. You can test different brands with different SPF ratings
2. Test the beads at different times of day or under different weather conditions to determine if the sun’s position or the amount of cloud cover impacts the rate at which the beads change color. 
3. Test the effectiveness of different filters like a car windshield, sunglasses, eyeglasses, house windows and car windows. Do you get different results with each?

How the Glow in the Dark Beads work....

• All glow-in-the-dark materials contain Phosphors, substances that radiate visible light after being energized.  Two of the most common places to see phosphors are fluorescent light bulbs and a television screen or computer monitor. In a TV screen, an electron beam strikes the phosphor to energize it. The screen actually contains thousands of tiny elements with phosphors that emit three colors -- red, green, and blue. In a fluorescent bulb, UV light energizes a mixture of phosphors together that create a light that appears white to us.
• Glow-in-the-dark products need a phosphor that is energized by normal light and has a long persistence (the length of time it continues to glow). Two of the most common phosphors used are zinc sulfide and strontium aluminate.
• Phosphorescent materials continue to glow after the energizing light is removed because they have electrons that are easily excited to higher energy levels when they absorb light energy.  The excited electrons do drop to a lower, but still excited, intermediate level where they stay for a period of time as they emit excess energy as visible light while they return to their ground state (original energy level).
• The return of electrons to their ground state is temperature dependent. A small amount of heat (thermal energy) is required to dislodge the electrons from their intermediate energy level and sent them to their ground state. If the phosphorescent material is very cold, for example liquid nitrogen, the electrons cannot return to their ground state and the material will not glow.  Glow in the Dark objects are also charged by UV light, even though it is invisible to the human eye. Try putting your beads in the freezer to test what effects the colder temperature has on the beads’ ability to glow in the dark.