2.1 (k)
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Demonstration 1
By this point you should already be using the phrases path difference, phase difference and coherence. For this first demonstration, you may wish to think of it as a 'thought demonstration'. So far a LASER has been used to create the visible light diffraction patterns, but why? The discussion can then lead onto how to create a diffraction pattern using for a single colour using a lamp - you need a light bulb, colour filter, single slit, double slit and then screen. It is worth doscussing the three phrases in this context. Next you may wish to take the idea a little further and deal with the diffraction of white light and the pattern you would expect to see.
