An electron in the n = 5 excited state of a hydrogen atom emits a photon of 1281 nm light. To what energy level does the electron move?

Any ideas on an equation for this? Is it some kind of backward version of Rydburg Eq?

4 answers

conver nm to energy.

E=h*c/lambda

then, having E, find the n.
h*c/lambda
would this be planck's constant times speed of light / wavelength?
Yes. Another way to do it
(1/wavelength) = R(1/n^2 - 1/5^2)
where R is the Rydberg constant. Solve for n.
How many photons of light are emitted when the electrons in 10 hydrogen atoms drop from energy level 5 to 3?