1) Fraunhofer lines are absorption spectra where photons of a certain wavelength
ID: 1626659 • Letter: 1
Question
1) Fraunhofer lines are absorption spectra where photons of a certain wavelength are absorbed by a gas between the photon source and a spectrometer/detector. One of these lines occurs for a wavelength of 517.27 nm and is due to the presence of magnesium in the gas; another magnesium absorption line appears at length 516.73 nm. What resolvance is necessary to resolve these lines from one another? Round to the nearest whole number. Submit Your submissions: 1 X Computed value: 1 Submitted: Saturday, June 10 at 11:36 PM Feedback: 2) An absorption line due to the presence of iron in a gas appears at 516.89 nm, between the two lines given in the previous problem. To resolve this line from the 516.73 nm um line in the first order diffraction pattern, how many more grating lines must be illuminated than in the previous problem? Round to the nearest whole number of lines lines Submit Your submissions: 1 X Computed value: 1 Submitted: Saturday, June 10 at 11:36 PM Feedback: Copyright o 2017 Freeman Worth Publishers a division of Macmitan Learning Chromatic Diffraction Resolving PExplanation / Answer
Solution 1:
Resolvance of spectrometer is given by,
R = wavelength/change in wavelength
= 517.27/(517.27-516.73) = 957.91
solution 2:
Resolvance = mN
where m is the order and N is the number of lines in the grating.
So, N = R/m = 957.91 lines
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