The separation of the colors is much larger than that obtained with a prism, so a diffraction grating can be thought of as a "super prism". When light of multiple wavelengths is used, the different wavelengths(different colors) are separated. If light of a longer wavelength is used, the maxima are at larger angles. When the pathlength difference is two wavelengths, another bright image occurs (the second order diffraction maximum). The first bright image to either side occurs when the difference in the pathlength of the light from adjacent slits of the grating is one wavelength, and it is called the "first order" diffraction maximum. Diffraction of a narrow beam of light of a single wavelength by a grating will produce a bright beam straight ahead and a series of beams to either side at angles where the light waves from adjacent slits reinforce each other. This is one way to confirm the basic theories about the wave nature of light.ĭiffraction through a series of closely spaced slits (called a grating) serves a useful purpose for the examination of the different wavelengths of light. If the diffraction pattern of the razor's edge is viewed in blue light and then in red light, it is found that the bright and dark bands are closer together in the blue light because its wavelength is shorter. Diffraction and interference in waves are the result of reinforcement or cancelation of waves when different waves are at the same point in space at the same time. The series of bands is called a diffraction pattern. For example, when the shadow of a razor blade is examined under high magnification it is found to be a series of closely-spaced bright and dark bands. When light is forced to go through a narrow slit or pinhole or when it passes a sharp-edged obstruction, it shows its wave nature. Interference and diffraction are traveling wave phenomena.
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