# what is the wavelength of light emitted when an electron in the hydrogen atom undergoes a transition from n=4 to n=2

Submitted by JSinfelt on Sun, 03/03/2013 - 13:56

How do you solve this equation?

You need the Rydberg equation. Type Rydberg equation into Google eg Wikipedia gives

$\frac{1}{\lambda_{\mathrm{vac}}} = R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$

Where

$\lambda_{\mathrm{vac}} \!$ is the wavelength of electromagnetic radiation emitted in vacuum,
$R\!$ is the Rydberg constant, approximately 1.097 * 107 m-1,
$n_1\!$ and $n_2\!$ are integers greater than or equal to 1 such that $n_1 < n_2\!$ and .

How do you solve? what numbers go where?