Question 363: Wave Optics

Question

If two sources emit light waves of different amplitudes then

Accepted Answer

When considering the interference pattern produced by two sources of light waves, the effect of having different amplitudes from each source is significant on the pattern's overall intensity but not directly on the fringe width. Interference patterns are typically characterized by regions of constructive interference (where the waves add up to produce a brighter region, or fringe) and destructive interference (where the waves cancel each other out, leading to darker regions or fringes).
Option A, "brightness of fringes is less," might seem like a potential effect of having different amplitudes. Indeed, if one wave has a significantly lower amplitude than the other, it might lead to a general reduction in the maximum brightness of the fringes, but this statement is somewhat vague and doesn't specifically describe the effect of amplitude difference on the interference pattern.
Option B, "fringes disappear after short time," is not accurate. The presence of fringes in an interference pattern is a result of the coherent phase relationship between the waves and does not directly depend on their amplitudes. The fringes will not "disappear" over time solely because of differences in amplitude.
Option C, "fringe width is less," is incorrect regarding what we're discussing. The fringe width in an interference pattern is determined by the wavelength of the light and the geometry of the setup (for example, the distance between the slits in a double-slit experiment and the distance from the slits to the observation screen). It does not depend on the amplitude of the waves.
Option D, "there is some intensity of light in the region of destructive interference," directly addresses the impact of having light waves of different amplitudes. In ideal conditions where two waves have exactly the same amplitude, the regions of perfect destructive interference would result in completely dark fringes, as the waves cancel each other out perfectly. However, if the waves have different amplitudes, even in regions of destructive interference, the cancellation will not be complete, leading to a nonzero intensity in what would ideally be a dark fringe. This is because the wave with the larger amplitude is not fully canceled out by the wave with the smaller amplitude.
Therefore, the most accurate statement related to the effect of having light waves of different amplitudes on an interference pattern is
Option D
: there is some intensity of light in the region of destructive interference.

Answer

brightness of fringes is less.

Answer

fringes disappear after short time.

Answer

fringe width is less.

Answer

there is some intensity of light in the region of destructive interference.

Wave Optics

If two sources emit light waves of different amplitudes then

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