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19_grab_bag11 - UCSD: Physics 8; 2008 1 Mixed Topics Mixed...

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Unformatted text preview: UCSD: Physics 8; 2008 1 Mixed Topics Mixed Topics Sunscreen/UV damage Sunscreen/UV damage 3D glasses 3D glasses UCSD: Physics 8; 2008 2 What does UV do that’s so bad? What does UV do that’s so bad? • Light comes in little bundles called Light comes in little bundles called photons photons • The energy of a photon is proportional to its The energy of a photon is proportional to its frequency: E=hf frequency: E=hf • UV is short wavelength, thus high frequency UV is short wavelength, thus high frequency – thus high-energy • UV photons have enough energy to destroy chemical UV photons have enough energy to destroy chemical bonds bonds – changes chemistry – pigments broken up → colors fade – can cause cancerous change to DNA in skin cell – Cause the bulk of skin damage we call “aging” – used in autoclaves to sterilize equipment (UV kills microbes) UCSD: Physics 8; 2008 3 Sunscreen Sunscreen • A coating of highly UV-absorbing molecules A coating of highly UV-absorbing molecules – UVB : 290–320 nm: sunburn – UVA: 320–400 nm: long-term skin damage, much of “aging”...
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This note was uploaded on 04/10/2008 for the course PHYS 8 taught by Professor Tytler during the Spring '08 term at UCSD.

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19_grab_bag11 - UCSD: Physics 8; 2008 1 Mixed Topics Mixed...

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