Chapter 24, Problem 55P

24.7 Skills for applying the wave model of light

Babinet’s principle Babinet's principle states that the diffraction pattern of complementary objects is the same. For example, a rectangular slit produces the same diffraction pattern on a screen as a rectangular obstacle of the same size as the slit, provided that the incident beam is wider than the slit or the obstacle. Determine the width of a hair that, when irradiated with laser light of wavelength 630 nm, produces a diffraction pattern on a screen with the first minimum 2.5 cm on the side of the central maximum. The screen is 2.0 m from the hair.