What Transition Does the Blue Line in Hydrogen's Spectrum Correspond To?

[InSpiRatioNy]

URGENT spectrum lines

Homework Statement

A diffraction grating (with 10,000 lines per cm) is held 2 meters from a Hydrogen lamp (lamp which emits
Hydrogen’s spectrum). As you look through the diffraction grating a blue line is observed to lie 1.11 meters on either
side of the lamp.
1) What transition (from initial n to final n) does this blue line correspond to?
2) What series does this line belong to?

Homework Equations

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The Attempt at a Solution

I've found these two relevant sites: http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
http://www.daviddarling.info/encyclopedia/H/hydrogen_spectrum.html But I'm still pretty confused with these two parts, I'm not sure where to start/what to do (I've already done all of the rest of the question)

 

[armis]

What you can work out from those two parts ( The generalized Balmer formula ) is your observed wavelength.

In which part of the electromagnetic spectrum is your observed colour? If I am now mistaken, once you know that, you'll be left with one uknown

 

[InSpiRatioNy]

I'm still confused, so I got theta = 0.51 rad and lambda (wavelength) = 485 nm, I know E = -13.6 eV/n^2

How do I determine what transition it is? How do I get it? I know how to determine the series after I get this.

 

[armis]

By now you should already know which series it is. In fact you didn't even have to solve anything to know which series it is as you were told the observed colour

Look up the generalized Balmer formula again:

\frac {1}{\lambda} = R ( \frac{1}{{n{_1}}^2}-\frac{1}{{n{_2}}^2})

You already know the wavelength. And after you figure out which series it is ( look up the drawing in this link again http://www.daviddarling.info/encyclopedia/H/hydrogen_spectrum.html ) you'll be left with one unknow which you have to find.

 

[InSpiRatioNy]

Is it a 4-2 tansition?

 

[armis]

Yep, if the wavelength is 485nm it should be 4-2

 

[InSpiRatioNy]

Perfect! Thanks!