5 Interference

5.1 General Remarks

In the last chapter, light was represented by using light rays. We could do this because the dimensions of the lenses and mirrors were very large compared to the wavelength of the light used. This area of study is known as geometrical optics. But, when the dimensions of the barriers or apertures become comparable to the wavelength of the light used, then we must consider light’s wave nature. This new area of study, called physical or wave optics, will be introduced in this chapter.

Since the energy in an electromagnetic wave spreads out continuously in space and time, two or more waves can interfere with each other. This can be thought of as light interacting with light. The other phenomena that we have already ...

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