Final answer:
Replacing a two-slit mask with a five-slit mask increases the complexity of the interference pattern, resulting in more secondary maxima and narrower, sharper primary maxima.
Step-by-step explanation:
If a two-slit mask is replaced by a mask with five slits, the interference pattern will be affected in terms of its complexity and detail. When the number of slits in a mask increases, the interference pattern generally becomes more intricate, with additional secondary maxima, which means that the answer to this question would be (b) Increases interference. This happens because each additional slit acts as a new point source of the waves, which overlap with the waves from other slits causing constructive and destructive interference at different points.
This is corroborated by Figure 3.10, which shows that as the number of slits increases, more secondary maxima (bright spots) appear in the interference pattern. However, it's important to note that while the overall complexity increases, the primary maxima (the brightest spots) become more narrowly spaced and sharper. The mathematics of interference detail how these patterns form due to the superposition of waves coming from different slits.