Rydberg's constant

[605823283]

I am just a little confused on why there are 2 different Rydberg's constant? Some times it is (1.0974*10^7) and other times it is (3.29*10^15)
And I might be wrong that they are both the Rydberg's constant, but they are used in the equation E=hR/n^2 so I am just confused when to use which one and why?

[Sristi Palimar 2E]

The two Rydberg constants differ according to what you are trying to solve for. The constant 3.28984(10)^15 s^-1 is used for the formula: frequency = R*((1/(n1)^2)-(1/(n2)^2)). This is the constant that is provided on the constants and equations sheet. The constant 1.097(10)^7 m^-1 is used for the formula: (1/wavelength) = R*((1/(n1)^2)-(1/(n2)^2)). This constant is not provided on the constants and equations sheet, but can be calculated by dividing 3.28984(10)^15 s^-1 by c, or the speed of light.
I would focus on remembering the Rydberg formula for frequency, since the Rydberg constant for frequency is given on the constants and equations sheet. You can always use the calculated frequency to determine wavelength by using the equation c= wavelength*frequency, so knowing the Rydberg constant for wavelength is unnecessary.

[haryn Shin 1H]

The two rydberg's constant is basically equivalent to each other, but they are just measured in different units.
R= 2.178 x 10^-18 J is in Joules (J), which is consistent with when we're calculating energy for example, while R= 3.29 x 10^15 Hz is measured in the unit of Hertz or s^-1, and is typically used when we're solving for frequency. Hope this helps!

[Madison Nguyen 3L]

Hello!

The difference between the two constants stem from its units. Both solve for frequency! The constant 3.29 x (10)^15 s^-1 is for R((1/(n1)^2)-(1/(n2)^2)) = frequency in Hz (s^-1) whereas the constant 1.097(10)^7 m^-1 is for R((1/(n1)^2)-(1/(n2)^2)) is in J.

[August Blum Dis 3D]

There are two different constants because the units of those constants are different. Thus, they are not simply equivalent numerically.

[Ishant Goel 2D]

Just to add on, you would use the respective equation based on the units you are trying to find in your answer. If you are trying to get an answer in Joules, you'll use the equation that gives you those units.

[Joseph Lee]

It's just different based upon whether you're using the equation with c/lambda, or if you are setting it simply equal to lambda, because if you divide the 3.289e-15 constant by the speed of light, you should find the other constant value!