The band pattern produced by light passing through a single slit depends on the:refractive index of the medium.slit width.wavelength.

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11ecba2d_130d_d136_a3bf_a5ae79185436_MD0008_00 Diffraction is broadly defined as the bending of light around edges or objects. Classic slit diffraction occurs as a uniform wavefront of monochromatic light arrives at a slit (ie, confined gap) in which the width of the slit (a) is comparable to the wavelength of the light (λ), resulting in the dispersed propagation of light away from the center of the slit. Diffraction through a single slit produces a pattern of dark and bright bands on a flat background surface distant to the slit. Bands occur when the bending of light causes the distance (path length) traveled by some waves to be longer than that of others. When the path lengths of two light waves differ by λ/2, the waves arrive at the background out-of-phase (ie, the peak of one waveform coincides to a trough of the other). As a result, destructive interference occurs such that dark bands in the diffraction pattern are produced. Conversely, light bands result from zero or minimal destructive interference. Dark bands (minimum light intensity) due to destructive interference occur when diffracted light waves pass through the slit at angles (θ) that are a function of the slit width and an integer multiple (m = ±1, ±2, ±3…) of the wavelength: 11ecba2d_130d_d137_a3bf_e17c1934c724_MD0008_00 sin θ=mλa According to this relationship, decreased slit width or increased wavelength tends to widen the band pattern such that greater distances are present between light and dark bands. Conversely, increased slit width or decreased wavelength results in a relatively narrow band pattern. Therefore, both slit width and wavelength influence the angle of propagation associated with the dark and light bands in the pattern of diffracted light (Numbers II and III). (Number I) The refractive index of the medium is relevant to refraction, dispersion, and other optical phenomena related to the passage of light between two media. However, the refractive index is not relevant to diffraction. Educational objective: Single-slit diffraction is an optical phenomenon that demonstrates the waveform nature of light. The band pattern associated with a given diffraction event is related to slit width and the wavelength of light.

The Band Pattern Produced by Light Passing Through a Single