We know light bounces and reflects through objects, but how is light actually created?


We know light bounces and reflects through objects, but how is light actually created?

In: Physics

Light is created at the atomic level. In really simple terms and from my limited knowledge of physics, an atom has electrons orbiting it’s nucleus. If we were to scale this up, we could think of our Sun as the nucleus of an atom. The planets in our solar system are the electrons orbiting this nucleus. Then imagine a giant orb surrounds all of the planets and the Sun with the Sun being at the center. This orb is the whole atom. So, these planets are orbiting the Sun inside this orb. They orbit at a specific distance from the Sun but if we were to energize the atom, it would force the planets into a higher orbit. Then as the planets fall back down to their normal orbit, they release that extra energy in the form of a photon. A photon is a form of energy that is visible and what we see as light. This is what’s happening inside our Sun and this is what happens inside a lightbulb. The filament inside the lightbulb is made of atoms and when we turn on the switch we’re energizing those atoms with electricity which causes the rise and fall in the electron’s orbits creating the release of photons and that’s how light is made.

When we say light, we’re actually referring to “Visible Light” on the electromagnetic spectrum. Basically… that’s a fancy way of saying radiation so light is pretty much the same as X-Rays, Radiowaves, Infrared (heat)…

In that way, it’s just a release of energy from an object. If it’s high energy (think Chernobyl) then it’ll be Gamma rays… think low energy (like burning gas) it’ll be things like infrared (heat).

In short, it’s just a reaction which gives off energy… like the electric current in a lightbulb meeting resistance… making the lightbulb hot (emitting Infrared) and giving out light (emitting visible light). So it’s just “created by” a reaction outputting enough energy that we can see it.

The law of thermodynamics state that energy can’t be created nor destroyed, so in a way it’s not “created” more “converted” from another form of energy which already exists.

A few ways, but generally it involves electrons accelerating.

One of the ways of modelling light is as electromagnetic waves, or ripples in an electromagnetic field.

Anything with charge (such as electrons) creates an impression in the electromagnetic field. And if those charged things are accelerating they will create ripples in the field.

You can think of it like the surface of a lake. Things with charge are stuff floating on the surface. If they start getting moved around that will create ripples on the surface. But different, because fields and so on.

How the electrons are moving around determines the frequency or wavelength of the ripples (how many ripples per second or how far apart the ripples are) and that tells you what colour the light is if it is visible, or if it isn’t visible, what type of non-visible light it is (infra-red, ultraviolet, radio waves etc.).

There are a whole bunch of ways to get electrons to move around; you can put them in a local changing electric field and force them to wiggle about (how radio transmitters work), or you can just give them too much energy so they wiggle about to lose it (why warm things glow).