Atomic Spectra

[Alondra Juarez section 1E]

In a hydrogen atom, an electron transitions from the fourth to the third quantum level. calculate the frequency of a photon emitted.

These problems seem to confuse me I know the problem indicates the n=4 to n=3 which means it decreased however I'm not to sure if I did it correct I used the equation En= -hR/n^2, after that I took out the -hr and got -hr (1/9-1/16) and I multiplied the constants as well as the fractions shown before and I acquired the answer -1.06 X ^-19 J and I know the answer is negative because it decreased levels but the problem also indicates to find the frequency how would I do that?

[Sara Veerman-1H]

When calculating for frequency, just make the value positive. The negative only indicates whether or not the energy is getting absorbed or emitted. It is not necessary in an equation for frequency.