### Rydberg Constant

Posted:

**Tue Oct 23, 2018 5:46 pm**I noticed there are two values that are used for the Rydberg constant (3.29x10^15 and 1.09x10^7). In which circumstances are each of them used when solving a problem?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=17&t=34670

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Posted: **Tue Oct 23, 2018 5:46 pm**

I noticed there are two values that are used for the Rydberg constant (3.29x10^15 and 1.09x10^7). In which circumstances are each of them used when solving a problem?

Posted: **Tue Oct 23, 2018 6:15 pm**

The Rydberg constant is 3.29 x 10^{15} when using frequency = R (1/n_{1}^{2} - 1/n_{2}^{2}).

Because c = wavelength x frequency, there is another form of the equation. Plugging in c/wavelength for what was frequency and rearranging the equation, we'd get: 1/wavelength = R/c x (1/n_{1}^{2} - 1/n_{2}^{2}).

The R/c value in the second value is the second (albeit, modified) Rydberg constant because R/c = 3.29 x 10^{15}/ 2.998 x 10^{8} which gives us 1.097 x 10^{7}.

So, really there only is one Rydberg constant. The second value you said is just Rydberg's constant divided by the speed of light as used in the second form of the equation. Hope this helps!

Because c = wavelength x frequency, there is another form of the equation. Plugging in c/wavelength for what was frequency and rearranging the equation, we'd get: 1/wavelength = R/c x (1/n

The R/c value in the second value is the second (albeit, modified) Rydberg constant because R/c = 3.29 x 10

So, really there only is one Rydberg constant. The second value you said is just Rydberg's constant divided by the speed of light as used in the second form of the equation. Hope this helps!

Posted: **Tue Oct 23, 2018 8:13 pm**

Thank you so much! ^^

Posted: **Tue Oct 23, 2018 8:48 pm**

No problem!