![]() ![]() Huygens' wave model of light also provides a plausible explanation to why waves diffract around an edge of an opaque material. The absence of wavelets on the periphery causes the wavefront to scatter and propagate outward. As a result, the new wavefront is formed from the interference between wavelets that managed to pass through the opening. When light travels through a slit, some of these wavelets are obstructed and can no longer propagate. In the 17 th century, Christiaan Huygens proposed that when a wave reaches an opening, its wavefront can be perceived as individual points emitting spherical secondary wavelets. Huygens’s wave model of light is commonly used to understand the effect of diffraction. Diffraction of light creates a unique repeating patternĭiffraction of light creates a repeating pattern where a white band is observed centrally and bands of rainbow are dispersed away from the centre, each separated by dark space.If the slit size is larger than light’s wavelength, diffraction still occurs but is unnoticeable to the naked eye.Įxamples of diffraction can be seen in all types of waves, including all electromagnetic waves, sound waves or waves observed in water.Smaller the slit, greater the degree of diffraction. If the slit size is smaller than or equal to light’s wavelength, considerable diffraction occurs.The degree of bend is dependent on the relative difference between its wavelength and size of the slit. The scattering process bends light’s direction of propagation. When light passes through an aperture, slit or around a bend/edge of an object, it also experiences this scattering effect, causing it to propagate outward. How to Do Diffraction related Calculation Questionsĭiffraction is the scattering behaviour a wave exhibits when it travels through a small opening or around the end of an object. HSC Physics SyllabusĬonduct investigations to analyse qualitatively the diffraction of lightĬonduct investigations to analyse quantitatively the interference of light using double slit apparatus and diffraction gratings dsinθ=mλ (ACSPH116, ACSPH117, ACSPH140)ĭiffraction & Young's Double Slit Experiment For the most part the wavfronts are not affected and continue to propagate in the direction of the rays, much like a beam of particles.īecause the wavelength of light is so small (400 to 700 nanometers for visible light), the diffraction of light around real world size obstacles and aperatures is very slight, explaining why for so long light was not thought of as having wave-like properties.This is part of the HSC Physics course under the topic Light: Wave Model. If the aperature is much larger than the wavelength, there is not much diffraction, and only the edges of the wavefronts bend slightly. If the aperature is around the size of the wavelength, or smaller, the waves spread out on the other side of the obstacle as if originating from a point souce in the aperature. ![]() ![]() Waves always bend around an aperature, however, the amount of diffraction depends on whether the aperature size is large or small compared to the wavelength. When a wave encounters a barrier with a small aperature, relative to its wavelength, it bends/diffracts and spreads out in a circular wave. When a beam of particles encounters a barrier, it either is stopped by the barrier, or passes through the aperature cleanly without any change in direction The bending of waves around corners that occurs when a portion of a wavefront is cut off by a barrier or obstacle. ![]()
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