Professor Merrifield largely "uncut" discussing refraction... Professor Moriarty on the same subject: https://www.youtube.com/watch?v=YW8KuMtVpug Visit our website at http://www.sixtysymbols.com/ We're on Facebook at http://www.facebook.com/sixtysymbols And Twitter at http://twitter.com/#!/periodicvideos This project features scientists from The University of Nottingham http://www.nottingham.ac.uk/physics/index.aspx Sixty Symbols videos by Brady Haran A run-down of Brady's channels: http://bit.ly/bradychannels Mike Merrifield tweets at https://twitter.com/ProfMike_M