College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 42

A laser produces a beam a few millimeters wide, with uniform intensity across its width. A hair is stretched vertically across the front of the laser to cross the beam. (a) How is the diffraction pattern it produces on a distant screen related to that of a vertical slit equal in width to the hair (b) How could you determine the width of the hair from measurements of its diffraction pattern