Let us take in our case a hydrogen atom with one proton and an electron in 1s orbital.
Now let us hit that electron with exactly only one ray of photon (Imaginary, don't know whether it is possible in reality) of frequency that would make the electron to jump to 2s orbital.
My question here is, now that the electron has jumped to 2s orbital there will be no photon (Imaginary) to make that electron to stay in the 2s orbital.
So the electron will jump back to 1s orbital emitting light.
When it jumped to 1s orbital, the ray of photon hits back the electron again, and the elctron jumps to 2s orbital and the cycle continues.
Is this possible if the given conditions are correct?