A plane monochromatic (λ=500nm) light wave normally falls on the diffraction grating, the period of which is d=0.01 mm, and the width of the transparent part α=2.5•10^-3 mm. How many maxima n will not be observed in the spectrum on one side from the zero maximum to the angle φ=30 ° due to the influence of the main maxima

A plane monochromatic (λ=500nm) light wave normally falls on the diffraction grating, the period of which is d=0.01 mm, and the width of the transparent part α=2.5•10^-3 mm. How many maxima n will not be observed in the spectrum on one side from the zero maximum to the angle φ=30 ° due to the influence of the main maxima