Due at the beginning of class on FRIDAY, May 15, 1998.
Chapter 38: 10, 11, 14, 21, 30, 47, 69
8. A two-slit interference-diffraction pattern is observed with light of wavelength 700 nm. The slits have widths of 0.01mm and are separated by 0.2mm. How many bright fringes will be seen in the central diffraction maximum?
BONUS: In a pinhole camera, the image is fuzzy because of geometrical optics effects of the pinhole and because of diffraction. As the pinhole is made smaller, the fuzziness due to its size (that is, due to rays arriving at the film through different parts of the pinhole) is reduced, but the fuzziness due to diffraction is increased. The optimum size of the pinhole for the sharpest possible image occurs when the spread due to diffraction equals that due to geometrical optics effects of the pinhole. Estimate the optimum size of the pinhole if the distance from it to the film is 10 cm and the wavelength of light is 550 nm. (Hint: To evaluate geometrical effects, consider the range of angles which can illuminate a point on the film.)