Correct units to derive Ryberg Constant in ev

[BWV]

Putting together a spreadsheet to calculate the hydrogen spectrum, cannot seem to get the right mix of units to get the Rydberg constant of 13.605... eV

also, what is the significance of R (1/n^2-1) converging to R as n gets large?

can anyone put this together or refer me to a source that lists this out? Going through my text and Wikipedia I am way off

 

[dextercioby]

I don't understand why this page http://en.wikipedia.org/wiki/Rydberg_constant can't help you. It contains everything you need.

 

[BWV]

I don't understand why this page http://en.wikipedia.org/wiki/Rydberg_constant can't help you. It contains everything you need.

Just looking for a what would comprise a consistent set of units for the constants in R, for example h is defined as either eV-s or J-s

 

[jtbell]

If you use MKS units (meters, kilograms, seconds, coulombs, and units derived from them) in the calculation, you should get energy in joules (J). Then convert to eV using the conversion factor 1 eV = 1.60e-19 J.

Otherwise you'll have to show us exactly what you've done already, so we can spot your mistake. Please do this in the Advanced Physics subforum of the "Homework & Coursework Help" forum, not here; this forum is for discussion, not help on specific assignments.

 

[BWV]

If you use MKS units (meters, kilograms, seconds, coulombs, and units derived from them) in the calculation, you should get energy in joules (J). Then convert to eV using the conversion factor 1 eV = 1.60e-19 J.
.

thanks, everything works but the conversion to eV

this is the equation I used and the units are not Joules. The wiki article says to multiply by hc but that is something like 10^-28 so you can't get to 13.6 eV that way

 

[dextercioby]

Well hc is approx 3*10^8 x 6.63*10^(-34) which is approx 2*10^(-25) which multiplied by 1.1*10^7 is approx 2.2*10^(-18) which devided by 1.6*10^(-19) is approx 13.6 in units of eV.

You may, of course, use a calculator for more precision, but I don't think it's necessary.

 

[BWV]

Well hc is approx 3*10^8 x 6.63*10^(-34) which is approx 2*10^(-25) which multiplied by 1.1*10^7 is approx 2.2*10^(-18) which devided by 1.6*10^(-19) is approx 13.6 eV.

You may, of course, use a calculator for more precision, but I think it's not necessary.

thanks, the last step was what I was missing