In the double slit interference pattern, the intensities of the maxima beyond th
ID: 1629777 • Letter: I
Question
In the double slit interference pattern, the intensities of the maxima beyond the central maximum are less than the intensity of the central maximum. Explain briefly why. ___ If you see a pattern of light and dark fringes on a screen, how can you tell if the pattern is due to a double slit or a single slit? Explain in terms of widths, not intensities.______ If you have a double slit having slit spacing 0.012 cm and slit width 0.003 cm, what would ______ be the first missing order maximum? How do the positions of the maxima in a double slit pattern depend on the slit separation: ______ linearly, inversely, or not at all?Explanation / Answer
(1.) The intensity decreases due to the inverse square law as it has to travel more distance away from the central maxima. At the spot of the central maxima, the path difference is zero. Whereas at the points either sides away from central maxima, the path difference for a bright fringe is an integral multiple of lambda/2.
(2) A single slit pattern contains intensity in a region. But there is also diffraction due to the single slit so you will have secondary minima on either side of the central maxima. In double slit pattern, you will have alternate bright and dark fringes of small widths due to the constructive and destructive interference of beams between the two slits. So in double slit the fringe width is very small.
(3) d=0.012 and b=0.003 cm then the ratio of d/b will determine the missing order. In this case d/b=4 ==> When the slit separation is integral multiple of slit width, teh condition for missing orders is satisfied. The 4,8,12th inteference maxima would be absent.
(4) the position of maxima will not depend on the slit separation. rather the intensities of the maxima/minima would depend on the slit separation.