Hi Guys, Because of the absorbtion and emmision spectrum we know that atoms have quantised engergy levels. For example for an electron to jump from ground state to the first excited state in a Mecury atom, a photon with the exact energy of 4.9eV is required. Now my question is what would happen if instead of a photon we fired an electron with 4.9eV of energy? Would the electron in the Mecury atom still jump to the first excited state? If so what happens to the incident electron?