How does interference occur in thin films? Why is it important that the films be thin? Why don’t you get these effects with a relatively thick film? Where should you put the dividing line between...

How does interference occur in thin films?

Why is it important that the films be thin? Why don’t you get these effects with a relatively thick film? Where should you put the dividing line between "thin" and "thick"? Explain your reasoning.

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Thin film interference exists when the thickness of the coating is approximately the same as a multiple of a quarter wavelength of light. Reflections of light can be made to add destructively by choosing a film thickness that is one-quarter of a wavelength. A quarter wavelength is choosen because a wave reflected from the second boundary traverses the length of the coating twice-- forward, and then backward. Hence, when returns to the first boundary, it is one-half of a wavelength (180 degrees) out of phase with the reflection from the first boundary. Thus the reflected light, which...

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