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Which objects or substances are best at blocking out ultraviolet rays? Hypothesis:The SPF 60 sunscreen will block out the most ultraviolet rays because that is what it is made to do. The UV-sensitive bacteria will thrive the most in the unprotected dish because there is nothing to block out the ultraviolet rays. I think the cloths won't do as well as the sunscreen, but better than the unprotected one. Procedure:
Materials: Pour the liquid agar into the seven petri dishes and let it solidify. After solidification, apply the bacteria broth to the agar in a two-inch circle in the center with a cotton swab, and let it cultivate for 24 hours. Lay three different dishes in the sleeve of the white, gray, and black shirts. Put plastic wrap on three different dishes and smear SPF 15, 48 and 60 sunscreen on the three different dishes. Leave one dish unprotected. Lay all seven dishes under an ultraviolet lamp, and turn the lamp on and leave it on for two minutes. After turning the lamp off, put the dishes in a dark place, and leave them there for 24 hours. After 24 hours, look at the bacteria in the dishes and record the growth. If there is little growth, let the dishes sit in the dark for 24 more hours. Record the amount of bacteria growth in each dish. Conclusion:My hypothesis was correct. The SPF 60 sunscreen worked better than the other sunscreens because it had the highest SPF level. Bacteria growth in the SPF 60 sunscreen dish was very light and very thin. Bacteria growth in the unprotected petri dish was very dark and thick. If I had done further experimenting, I could have found which substance would work best over an extended period of time, such as five or ten minutes of exposure instead of two. Biblical Application:1 Corinthians 6:19 says, "Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own? The bodies of believers are temples of God. Because of that, we should protect our bodies. We can protect our bodies by wearing sunscreen and light clothing. |
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300 Cromwell Street, Phillipsburg, New Jersey 08865 |
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2nd Place, 8th Physical Science, PCA Science Fair