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Unformatted text preview: 35. The ruling separation is d = 1/(400 mm−1 ) = 2.5 × 10−3 mm. Diﬀraction lines occur at angles θ such that d sin θ = mλ, where λ is the wavelength and m is an integer. Notice that for a given order, the line associated with a long wavelength is produced at a greater angle than the line associated with a shorter wavelength. We take λ to be the longest wavelength in the visible spectrum (700 nm) and ﬁnd the greatest integer value of m such that θ is less than 90◦ . That is, ﬁnd the greatest integer value of m for which mλ < d. Since d/λ = (2.5 × 10−6 m)/(700 × 10−9 m) = 3.57, that value is m = 3. There are three complete orders on each side of the m = 0 order. The second and third orders overlap. ...
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.
- Fall '08