What happens when an electromagnetic wave strikes an excited atom?

When an electromagnetic wave strikes an excited atom, the interaction often leads to the transfer of energy to the atom. This process can cause the atom to move to a higher energy state or, in some cases, to transition to a lower energy state while emitting a photon.

In this context, the statement about transferring energy is key. If the frequency of the electromagnetic wave matches the energy difference between the excited state of the atom and a higher state, the energy can be absorbed temporarily. This would make the wave appear larger in amplitude as the energy is accumulated in the atom.

It's important to note that the correct understanding of this interaction also involves recognizing the limitations of absorption. Not every interaction will lead to the wave being completely absorbed; rather, it is common for some of the energy to be re-emitted as a photon, which corresponds to the transition between energy states.

This dynamic explains why energy transfer is an integral part of how excited atoms interact with electromagnetic waves in physics and various applications such as lasers and spectroscopy.