Question

For a double slit Fraunhofer diffraction pattern, find the missing orders if the widths are 8.8 Å and 4.4 Å apart. Light from sodium vapour lamp is incident normally on a grating 0.2 cm wide with 2500 lines. Calculate the angular separation between the two sodium lines. λ1 = 5270 A.U. and λ2 = 7665 A.U.

Answer 1

Answer:

There's a good discussion of this in Wikipedia under “Diffraction Grating”. In brief, if the number of lines per cm in increased and thus the spacing of the lines d is decreased then the angle from the incident light where a given wavelength appears will increase.