Here’s what I understand:
1. Light is photons.
2. Photons are created when an electron moves from a higher energy orbital to a lower energy orbital (loses energy).
My question: what causes this constant source of (energy loss of electrons?) photons? When I turn on a light, light is emitted constantly. This means that electrons are continuously dropping in orbital levels emitting a constant stream of photons creating light. Let’s take the incandescent light bulb for example. I send current into a filament to heat it up due to its resistance. The filament gets so hot that it glows, producing light. Likely due to my lack of complete understanding of particle physics, I see we are introducing a continuous form of energy, and it makes sense that tons of electrons would begin moving up orbitals as they’ve become excited. What is causing this same constant drop of energy of other electrons entering the lower orbitals. My question might even be better phrased, what causes electrons to drop into lower orbitals?
In: Physics
**Multiple replies have given you the same incorrect answer** – that light is emitted when electrons go to a higher energy state and fall back down. That process does emit light (it is how a fluorescent lightbulb or an LED works), but that isn’t what is happening with an incandescent bulb.
An incandescent light works by sending a lot of electricity through a very small wire – the filament. Any normal material has a certain amount of electrical resistance to it, as the electrons moving through it bump around and cause things to wobble and move, which at the macro level means converting energy to heat. The engineering marvel of the lightbulb is that it lets something very small get VERY VERY hot over and over without breaking.
The light that the filament produces is **thermal radiation**. All objects are giving off thermal radiation all the time, but the amount and the spectrum of wavelengths produced depends on temperature. Room temperature stuff gives off mostly infrared, which is why we sometimes call an infrared camera a “thermal camera.” Hotter stuff, like a flame, the sun, or an incandescent lightbulb, give off mostly visible light.
So what is thermal radiation? Basically, all the molecules are wobbling around and vibrating and bumping into each other. These molecules are made of atoms and the atoms are made of subatomic particles, including electrons and protons which have their own charge. Things which have their own charge have their own electric field, and that field is constantly shifting around as the atom does. Light is essentially waves in the sum of all those electric fields put together, created by their random motion added together, just like ripples in a pool full of people thrashing around.
That is why an incandescent bulb generates ALL frequencies of light at once, since it’s caused by random motion, NOT by an electron falling from on specific energy state to another.
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