Waves oscillate, but why doesn’t the energy dissipate in oscillation(does oscillation not require energy? is it perpetual?) (2) In a laser, upon providing charge the electron gets excited and after releases a photon, but if we are continuously providing energy, why does it “de-excite”

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I was reading how lasers work and it said that when you provide charge to an electron it gets excited and moves to an unstable higher state, and after trying to get into an stable state it looses energy in the form of a photon(The first question is from this part), but if we are continuously providing energy to the electron(like, we are keeping the button pressed) then shouldn’t the electron keep itself in the unstable state unless we switch off the button?

2) Mechanical wave oscillate due to physics, but the electromagnetic waves oscillate due to electro magnetic field(From the answers – [https://www.reddit.com/r/explainlikeimfive/comments/l8jdan/comment/gldh94z/?utm_source=share&utm_medium=web2x&context=3](https://www.reddit.com/r/explainlikeimfive/comments/l8jdan/comment/gldh94z/?utm_source=share&utm_medium=web2x&context=3)) but if they are mutually producing each other as an effect of each other, do they have the efficiency of 1? like, light in vacuum travels endlessly and we are able to receive radio waves from so far away in space, so does oscillation not consume any energy(The answers on the internet are very vague, some say they loose energy by 1/r2 where r is amplitude, the other said that in vacuum they can travel forever in theory)?

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Anonymous 0 Comments

Some oscillations don’t lose energy, because they don’t interact with anything outside of themselves.

You do need to keep the proverbial button pressed for a laser to work, because an atom in the ground state will absorb a laser photon instead of emitting another one. So you need to maintain a population inversion, i.e. most of the atoms must always be in an excited state.

Anonymous 0 Comments

? Waves are complicated? Is the question asking how do waves remain energized? Well EM will travel forever until it runs into something that absorbs it, the intensity is what we actually measure, and this intensity decreases with the inverse square law ? As for lasers, essentially a photon forces an electron down an energy level and results in the stimulated emission of two identical photos?