![]() Higher frequencies will generally cause distortion with less amplitude, so sweeping up in frequency should be compensated by reducing the amplitude slightly. Start by driving the dipper at a small amplitude and slowly increase it until distortion or splashing occurs, and then back it off from that point. Adjust the height of the driver as necessary. The dipper should be only partly submerged. ![]() After use the water can be drained through a hose attached to one of the corners of the tank. When preparing for a demonstration of refraction, use the leveling scews near each edge of the tank to make sure it is perfectly level, and be careful to add just enough water to cover the inserted plastic. Place absorbent rags along the perimeter of the tank to prevent unwanted reflections. ![]() Once the apparatus is set in position, fill the tank with about an inch of water. Make sure the entire class can view the image on the screen. The angle of the mirror should be adjusted so that the entire tank is visible on the screen. The mirror and screen can block a significant portion of the blackboard, so if one plans to use the boards the apparatus should be placed off to the side. Extra time should be allowed for wheeling it into a hall. Obstacles can be placed to interact with the rippling water a single barrier can show edge diffraction multiple barriers can show sinlge or multi-slit patterns a triangluar peice of plexiglass acts as a prism a convex peice brings the wavefronts to a focus. A horizontal dowel can produce coherent parallel wavefronts. The height of the driver above the water can be adjusted to accommodate different dippers. To show these ripples, bright light from a xenon arc lamp shines through the tank's glass bottom, reflects off a one square meter front surface mirror, and illuminates a large, thin screen that hangs vertically. When the driver is driven by a function generator, the dipper causes ripples in the water. A dipper, suspended from an 8 Ohm speaker driver, is partially submerged. Various wave phenomena demonstrated with water waves: circular waves from point sources, plane waves from an array of point sources, change of wavelength with frequency and/or speed, reflection of waves, refraction of waves, focusing of waves, standing waves, interference from point sources, interference and diffraction from apertures, obstacles, and barriers, phased arrays of sources (directional plane waves), beating phenomenon, doppler shift, and shock waves.Ī shallow, one square meter glass-bottomed tank is filled with a couple inches of water. The views expressed in the project do not necessarily reflect the views of The Office for Learning and Teaching.Interference patterns of water waves generated by different sources at adjustable frequency. Support for this project website has been provided by The Office for Learning and Teaching, which is part of the Department of Industry, Innovation, Science, Research and Tertiary Education. Single slit diffraction, diffraction gratings.ĭownloads (thumbnails at 50% of size of animation) Recreating a hologram: coherence beam and hologram plate. X-ray diffraction.įorming a hologram: beam splitter, object and reference beams, interference at the film. ![]() Diffraction requires wavelengths less than 0.1 nm. The atomic lattice as a diffraction grating. When is the eye diffraction limited? The resolution of telescopes. Resolving two point sources: Rayleigh's criterion. Diffraction pattern from a circular aperture. Rayleigh criterion and the Airy disc: Aperture and resolutionĬircular apertures in optics. A modern recreation of Arago's experiment. The bright dot at the centre of the shadow: Poisson's argument against the wave nature of light. The hydrogen spectrum and the origins of quantum mechanics. Continuous spectra and line spectra, absorption and emission spectra. Young's experiment with finite slit width: I q shows both interference and diffraction effects.Ī light-hearted discussion to illustrate why we don't notice quantum interference in everyday life.Īdding phasors with 2, 3, 4 and many slits: Diffraction gratings. Young's experiment with finite slits.ĭiffraction from a single slit:Huygens' construction. X-ray, neutron and electron diffractionĭiffraction from a single slit. Shadows and beams with water waves of short wavelength. Diffraction, shadows, beams, Huygens' construction.ĭiffraction of light and sound.
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