In a Young's double-slit experiment, a set of parallel slits with a separation of 0.100 mm is illuminated by light having a wavelenghth of 589 nm, and the interference pattern is observed on a screen 4.00 m from the slits. (a) What is the difference in path lengths from each of the slits to the location of a third-order bright fringe on the screen? (b) What is the difference in path lengths from the two slits to the location of the third dark fringe on the screen, away from the center of the pattern?
Explanation / Answer
separtion of the slits d = 0.1 m m wavelength = 589 nm = 589 * 10 ^ -9 m distance of the screen from slits D = 4 m ( a). for 3 rd order bright fringe pathdifference = 3 = 1767 * 10 ^ -9 m (b). path difference = 5 / 2 = 1472.5 * 10 ^ -9 m