When an electron falls from a higher to a lower energy level in an atom, the photon released has a wavelength of 121.6 nm. what is the energy difference between the two energy levels, in j?

Explanation:

The energy difference between the energy levels involved in the transition of the electron is directly proportional to the frequency of the emitted photon:

Where h is the Planck constant. The photon's frequency is inversely proportional to its wavelegth:

Here c is the speed of light. Replacing (2) in (1):

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.