Announcements . Happy Groundhog Day! . Pick up old labs at the end of class . Why not start preparing now for the final exam? ÆRead through the old lab again, making sure you know the answers to the quiz questions ÆTake another look at the lecture notes (on the web) and see if they now make more sense . We were lenient in the grading . In the future, be sure to ÆAnswer question explicitly being as quantitative as possible ÆShow your calculations ÆRarely (if ever) will more that 3 sig figs be appropriate Light - Some History . Early 1800's: Light is a wave traveling through the aether (not quite right) . 1865 James Clerk Maxwell: Light is a wave of electromagnetic radiation (yes) . 1905 Albert Einstein: Light is both a particle and a wave (amazing but true) wavelength, ? PARTICLE WAVE Electromagnetic Spectrum . All electromagnetic waves travel through vacuum with a speed c (3 X 10 8 m/s) . The visible portion of the spectrum forms a tiny portion of the total EM ...