Hi,

I'm sort of new to this forum, but at my university there are sadly no tutors nor other resources to assist in my physics difficulties, so I hope you all can help me. Here is the question:

The wavelengths of the two yellow sodium lines are 5890 nm and 5896 nm. The eye, with the aid of the spectrometer telescope, can resolve an angle of 0.2 min. How many lines per metre must there be in a diffraction graving for the two sodium line to be seens as just separate in the first order in the spectrometer? Assume the diffraction angle is smalls so that sin (theta) is approximately (theta) in radians.

I was trying to figure about whether this is only about diffraction grating or also the mechanisms of using the spectrophotometer...but I'm stumped.

I can only think of the relationships of

d*sin(theta) = m(lamda)

change in y = Ltan(theta)