(A) A laser beam with wavelength ? = 6328 Å is incident normal to the plane of a diffraction grating. The grating has 550 lines per mm. If the diffraction pattern is viewed on a screen 10 cm from the grating, find the distance between the two first- order maxima in the pattern.
(B) A laser beam with wavelength ? = 6328 Å is incident normal to a single slit of unknown width. The diffraction pattern as shown in the figure is formed on a screen 80 cm from the slit. Find the width of the slit.