Final answer:
If the length and width of a single slit are comparable, the diffraction pattern becomes more pronounced and complex. The pattern varies with slit width and is most defined when the slit width is similar to or smaller than the light's wavelength. Increasing the slit width leads to increased spacing between diffraction bands. a) The diffraction pattern becomes more pronounced is correct answer.
Step-by-step explanation:
When studying diffraction by a single slit, the assumption typically is that the length of the slit is much larger than its width. This simplification helps in understanding the pattern created when light passes through such a slit. If the length and width of the slit are comparable, the diffraction pattern changes significantly. Specifically, the diffraction pattern becomes more pronounced and more complex.
As the slit width is reduced relative to the wavelength of light, the central maximum in the diffraction pattern becomes wider, and the overall pattern becomes more spread out. The diffraction pattern is most defined when the width of the slit is on the order of, or smaller than, the wavelength of the light being used.
A larger slit width compared to the wavelength will produce more intricate diffraction effects, including multiple maxima and minima within the pattern. If the question is about what happens if the two dimensions were comparable, the answer is that the diffraction pattern becomes more pronounced (a).
However, if the question is about what happens when the slit width is increased, the spacing between the diffraction bands will also increase.