The distance between the ruled lines on a grating is 1770 nm.The grating is illuminated at normal incidence with a parallel beam of white light in the 400 nm to 700 nm wavelength band.What is the longest wavelength that appears in the third order spectrum?

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Quizplus · Accepted Answer

The longest wavelength in the third order spectrum is found using the grating equation: d*sin(θ) = m*λ. For maximum wavelength, sin(θ) = 1, so λ = d/m. Here, d = 1770 nm and m = 3, giving λ = 1770 nm / 3 = 590 nm.

The Distance Between the Ruled Lines on a Grating Is