where do the photons produced by a lightbulb come from??

Question

according to physicists all matter is already in existence so where do these pesky photons come from?? in the bulb there are electrons protons and neutrons making up the atoms of the metal and glass of the bulb but i don't see where the photons come from? i understand how they are produced but not why and where from

Answer 1

I have no physics degree but I think this might help you. The answer will vary slightly depending on how contemporary the physics you use to answer it is but here is an inexact answer which should give you the general idea.

So the first thing you need to know is that all matter is not in existence already. Matter is energy in a special form where it is sort of tied up in a wiggly knot. You can see the relation between the two in einstein's

m=E/c^2 (just an alternate form of E=mc^2)

where
m is mass(the property that quantifies matter)
E is energy
c is the speed of light

So from that there is an equivalence between matter and energy. Matter can be created by knotting up energy, or destroyed by liberating the energy it was made with.

So, without going into really advanced physics, all mass is not conserved (meaning it can be created or destroyed) but energy IS conserved, there are all kinds of rules involved, but you can interchange the two of them.

When you release energy as photons from matter you are converting some of that matter (tied up energy) into energy. If you could weigh the matter that radiated the photons well enough you would be able to see that it weighs less!

In "pair production" a photon can create matter; an electron and positron.

Another example of energy being released from matter is nuclear fission. Where the matter going in weighs more than the matter after the process. The difference of mass is the energy freed from the uranium fuel.

It's like the photon is some of the stuff that the electron is made of... (this is a loose analogy) like some of the waggling rope that the electron knot was made of. The electron knot can lose some excitement (energy) by shedding a section of the length of the rope(photon) which goes zipping away as pure electromagnetic energy.

All the abstractions like neutron, proton, electron, photon aren't really such absolute and fundamental things that are seperate and different from each other. They are more like energy tied up in different ways.

Answer 2

This might be a bit hard to understand, since it borders on quantum mechanics and wave/particle duality, but I will try to make it as simple as possible.

All particles can be represented by a wave, and all waves can be represented by particles. The term "photon" is used for the particle counterpart of electromagnetic radiation, i.e. light.

Of course you know that photons have no mass, and therefore do not need to "come from" anywhere, but they are simply an excess of electromagnetic energy emitted when excited electrons in higher orbitals fall down to lower orbitals in the atomic structure, meanwhile giving out energy. This energy is in the form of electromagnetic radiation, and the electromagnetic waves are represented by photon particles.

It does not neccessarily have to be electrons losing energy to emit photons. Actually, everything that has a temperature above absolute zero (-273 C) emits so called "blackbody radiation" in the form of electromagnetic waves, and hence photons. Of course, the higher the temperature, the higher the intensity, and the frequency of the radiation also change with the temperature.

Thus, for a light bulb filament heated up to a certain temperature by putting current through it, the frequency of electromagnetic radiation is at highest intensity at around that frequency corresponding to yellow, however, a lot of energy is also emitted in other frequencies not only within the visible spectrum (infrared for example, heating up things around the light bulb).

Answer 3

You are mistaken in the statement that physicists say all matter is already in existance. In fact, physicists think that matter can be created and destroyed using energy. It is ENERGY that is not created or destroyed. Although I don't think photons could be considered a form of matter...since photons are just chunks of light energy...the energy used to make the photons ultimately comes from the heat energy caused by the electricity flowing through the wire in the light bulb.

Answer 4

keeping it simple (hopefully), and maybe a wee bit off the mark

the atoms in the wires of a bulb are given energy when electricity flows. this raises the electrons into many different higher orbits. after a certain time the electrons (which don't like being in these orbits - always want to go to lower orbits) drop back down into lower orbits. there is an energy difference between these two orbits and when the electron 'drops' it gets rid of an amount of energy equal to this difference. this energy is emitted as a photon and the colour of the light is determined by the amount of energy (violet colours/frequ having more energy than red colours/freq). white light is created by having lots of different 'drops' of different magnitude, laser light is made by having only one 'drop' - giving one colour

more complex if you are wanting to know why given out as a wave packet, or bundle of energy, but i'm not sure what u were exactly aiming for

Answer 5

First, photons are energy, not matter. The light filament, like all hot matter, radiates energy away in the form of photons. The energy came from the electricity running through the filament; you can trace that back to the big bang if you like.