# A diffraction grating gives a second-order maximum at as angle of 31�‹ for violet light (ƒÉ = 4.0 �~ 102 nm). If the diffraction grating is 1.0 cm in width, how many lines are on this diffraction grating?

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1. Sorry about the double post, and
the question is:
A diffraction grating gives a second-order maximum at as angle of 31 degrees for violet light (wavelength = 4.0 x 102 nm). If the diffraction grating is 1.0 cm in width, how many lines are on this diffraction grating?

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2. n lambda = d sin( theta )

d=n * lambda/sinTheta

solve for d. That is the distance between slits, so lines/distance= 1/d

change wavelength to cm if you want lines per cm

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3. isn't that derived from the formula used for single slit though? and this is multiple slit (isn't that the same eqns as double slit?

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4. so n= 2 (second order)
theta= 31 degrees
d= 0.1 m
lambda= 4.0 x 10^-7 m

(i'm required to solve in m)

is this correct?

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5. no

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