Multiple Slit Diffraction This animation will deal with diffraction of a particle beam with Realistic Parameters The learner should definitely click the link below for a full discussion of this subject. Louis de'Broglie in 1924 postulated that, since light can behave both as waves and particles, massive particles must also be accompanied by waves of wavelength lambda=h/p where h is Planck's constant and p is the particle momentum. Therefore we expect to be able to observe diffraction effects when the guiding wave is incident on a slitted screen. The initial screen was actually a very thin gold foil but we will use a slitted screen here to show the diffraction effects of Particles. This animation shows how the diffraction peaks can be observed even when the particles arrive at the screen one at a time. The wave is shown traveling as a gaussian wave packet toward the screen. An interesting variation of this animation is that the incident waves are not all directed exactly normal to the screen but have a user-selectable range of angles. This range of angles broadens the peaks and makes the results more realistic. The resulting peaks occur at a distance much greater than the slitted screen width from the screen. The learner must wait for the particle diffraction peaks to build up in order to understand them. After changing the slit spacing, the peak distribution plot is erased since the separation of the peaks will change. The profile of the expected particle distribution is plotted in blue. The learner is free, over a range of 2-24, to select the number of slits. However, when the number of slits is changed, the program automatically adjusts the slit spacing (and therefore the displayed wavelength) to keep the total width of the slitted region equal to the beam width. Here is an animation that attempts to show the wave-particle duality by showing what happens when a wave is incident on a screen with multiple slits. The particles can be massless photons or massive particles like electrons or protons. The wave can be an electromagnetic wave like light or a Schrodinger wave like those of quantum mechanics. It has been shown by experiment that, even if just one particle at a time goes through the screen, the particles still form the expected wave-like distribution when they are collected on a screen that is distant from the slitted screen. Since the distribution on the distant screen would build up too slow if we showed just one particle at a time approaching the screen, I have chosen to show at least 10 particles in what I will call a wave packet pulse. The green wave packet is a gaussian distribution envelope function that encompasses a sinusoidal magnitude variation. This gaussian distribution has the lowest product of momentum and position that is possible in quantum mechanics. What happens when the plane continuous wave fronts impact the slitted screen is that each slit acts as a source of a new cylindrical wave front centered at the slit and of growing radius as the front continues away from the slit. This wave front is actually curved but for display speed I chose to show it as straight lines. It is the random interference between these many new wavefronts that creates the intensity profile at the distant screen.
Click Here for Diffraction Equations mMax nParticles slitWd nSlits lambda Single Step