An electron jumps from energy level 1 to energy level 2 by absorbing a photon of energy 8 eV. What is the most likely energy of the photon that will be emitted by the electron when it moves back down to energy level 1?
The photon it emits most likely will have an energy of 8 eV, also. The energy level difference is the same whether you're gonna be absorbing or emitting.
