[Q11.4, highly recommended for practice] Double-slit challenge question. Red light with wavelength 700 nm is passed through a two-slit apparatus. At the same time, monochromatic visible light with another wavelength passes through the same apparatus. As a result, most of the pattern that appears on the screen is a mixture of two colors. However, the center of the third bright fringe (m = 3) of the red light appears pure red, with none of the other color. (a) What are the possible wavelengths of the second type of visible light? (b) Do you need to know the slit spacing to answer this question? Why or why not