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Originally Posted by ratbastid
Here's my question: Light waves were depicted the same way in my High School physics book, as a sine wave. But I'm not clear what the actual physical mechanism of light wave propagation is. I know that "light behaves as both a wave and a particle", but that doesn't give me much of an understanding.
Somebody who's up with physics answer this: HOW does light behave as both a particle and a wave? I understand there's such a thing as a photon, but I don't know quite what it is or how it works. And that's the particle side of the equation; tell me also about the wave part.
And then... tell me about light wave polarity. How do light waves work (again, in the real world, not in physics textbook simplifications) such that my polarized sunglasses filter out light that has been reflected?
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Hey, I used to wonder exactly the same things you are! At least you understand what a pressure wave is (like sound). I don't think it's any different for electromagnetic waves.
Suppose you have an object with a certain amount of charge. Assuming you understand what force fields are, that object will have an electric field around it, extending to infiinity (barring obstructions, of course). Note that the field is oriented. This reflects how the force caused by the charge must do so in a specific direction. This will be important, later. For now, we will examine what happens when we move the charged object (in some direction). The electric field will change and this change will propogate through space (can you guess at what speed?). Can you see how this propogation is a wave very similar to your pressure wave?
As far as I can tell, the only difference between this wave and a pressure wave is that this wave is oriented because the thing that's propogating (electric field strength) is oriented. It's this orientation that allows this wave to be polarized. If we examine a path of the wave (the electric field propogated in all directions) perpendicular to the movement of the object, you will see how the orientation of the field can be in one direction before the wave front and then the other direction after the wave front. Thus, the wave has an orientation in 3 dimensions. It turns out that the diagram in your book wasn't so far off, after all...
I hope this no nonsense explanation helped ground these abstract ideas into reality!