The Effects of Distance From the U.V. Light Source on Color Changing Beads! As you have learned, U.V. Beads change colors when exposed to U.V. radiation be it from the sun or a U.V. lamp ( Black Light!). Purpose: To see what effects the distance from the U.V. light source has on the color changing of the beads. Materials needed: U.V. Lamp, Strand of 5 Beads , ruler Procedure: work in groups of 3-4 ( each student will still answer the questions and fill out pertinent information on this page) 1. Obtain a strand of beads and a ruler 2. Move one bead so that it is at the end of the pipe cleaner strand, and then space the remaining beads out – 3-5 cm apart. Record the distances on the data table 3. Place the bead strand on the table under a U.V. light as directed by your teacher. 4. When directed to, turn on the light. Your teacher will say when to turn off the light. 5. When directed to, remove the bead strand from the light source and make and record observations about the color changes on your data table. ( observations such as darkness / intensity of color, uniformity of color-(( note that the “down” side of the bead may have not changed color like the “up” side)) ) Bead: Distance from end (cm) Observations/ color change/ intensity etc. 1 2 3 4 5 Control n.a. bead Questions/ analysis ( complete well written sentences) 1. What was the Independent Variable in this experiment? 2. What is the Dependent Variable? 3. What purpose did the control have? 4. Describe the results of the experiment. Bonus: Graph your data 5. What do you think would have happened if the light was left on for 3 or 4 times as long as it was? 6. What do you think would have happened if a piece of Kleenex tissue was placed over the beads? 7. What do you think would happen if a piece of plastic was placed over the beads? 8. What is the effect of UV radiation on people? 9. What do people do to protect ourselves from U.V. radiation? 10. What other variables could have been used in a lab like this one?