Diffraction and interference experiments with narrow slits play an important role in helping students understand many properties of light. Of special interest is the diffraction experiment suggested by PSSC physics. Slits made with two razors can have large errors, and commercial slits may not offer the variety of slit widths needed to obtain specific diffraction patterns. We show how slits can be made more easily and inexpensively with graphic arts films with errors of less than 5%.

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