The screen S is placed parallel to the slit for observing the effects of the diffraction of light. The slit AB of width d is illuminated by a parallel beam of monochromatic light of wavelength λ. The figure shows the experimental arrangement for studying diffraction of light due to the narrow slit. See Also : Interference of light Diffraction due to Narrow slit The diffraction of light occurs, in effect, due to the interference between rays coming from different parts of the same wavefront. The phenomenon is found to be prominent when the wavelength of light is compared with the size of the obstacle or aperture of the slit. These two experiments clearly show that when light travels past an obstacle, it does not proceed exactly along a straight path, but bends around the obstacle. According to Huygens’s principle, each point on the rim of the sphere behaves as a source of secondary wavelets which illuminate the central region of the shadow. The shadow of the spherical object is not completely dark but has a bright spot at its centre. Another simple experiment can be performed by exhibiting the same effect.Ĭonsider that a small and smooth ball of about 3 mm in diameter is illuminated by a point source of light.The shadow of the object is received on a screen as shown in the figure. If light travels in a straight path, the central region should appear dark i.e., the shadow of the screen between the two slits. In Young’s double-slit experiment for the interference of light, the central region of the fringe system is bright. See Also: Refraction of light Diffraction of light The convex lens is not needed to converge the spherical wavefronts.Wavefronts leaving the obstacles are also spherical.Source and screen are not far away from each other.Diffraction also occurs in a bending movement where the wave becomes more spread out This pattern is unique to the type of crystal and can be used to identify the molecule that makes the crystal. The crystal diffracts the X-ray and makes a diffraction pattern. In X-ray crystallography, X-rays are aimed on a crystal. Diffraction gratings are used in many analytical chemistry tools, such as a spectrometer.ĭiffraction can also be used to look at molecules using X-ray crystallography. Diffraction gratings work because different wavelengths of light will constructively interfere at different angles. A diffraction grating can be a series of closely-spaced slits or a mirror with a series of small grooves. Uses of diffraction ĭiffraction can be used to separate different wavelengths of light using a diffraction grating. The strongest examples of diffraction occur in waves where the wavelength is similar to the size of the object causing diffraction. These patterns of interference rely on the size of the diffracting object and the size of the wave. When interference is destructive, the intensity will decrease, sometimes to a point where it is completely destroyed. When interference is constructive, the intensity of the wave will increase. Interference can be either constructive or destructive. This shift will cause the wave to have interference with itself. ![]() ![]() ![]() The wave that passed through the slits was diffracted and will interfere with itself.ĭiffraction is caused by one wave of light being shifted by a diffracting object.
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