wedge-shaped layer of air will exist in the middle, with a thickness that changes gradually from one end to the other. What would you expect to see if the slides were illuminated from above by light of a single color? How would this change if you gradually lifted the lower edge of the top slide until the two slides were finally parallel? ? An observation like the one described in discussion question C was used by Newton as evidence against the wave theory of light! If Newton didn't know about inverting and noninverting reflections, what would have seemed inexplicable to him about the region where the air layer had zero or nearly zero thickness? o / The period of this double-pulse pattern is half of what we'd otherwise expect. / Any wave can be made by superposing sine waves. q / Graphs of loudness versus frequency for the vowel "ah," sung as three different musical notes. G is consonant with D, since every overtone of G that is close to an overtone of D (marked "*") is at exactly the same frequency. G and C? are dissonant together, since some of the overtones of G (marked "x") are close to, but not right on top of, those of C?. r / If you take a sine wave and make a copy of it shifted over, their sum is still a sine wave. The same is not true for a square wave. t / Surprisingly, sound waves undergo partial reflection at