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This question already has an answer here:

I have always been interested in Physics, and lots of people say that light is a particle and a wave.

How is it possible? How can a photon (a light particle) be a wave as well, when its a particle?

I have tried looking this up, but I do not really understand the answers, as they are quite complicated to me. If you could answer this, please could you explain it in quite a simple way!

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marked as duplicate by DumpsterDoofus, Kyle Kanos, Brandon Enright, WetSavannaAnimal, John Rennie Mar 19 '14 at 6:51

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First, we need to ask ourselves what exactly do we mean when we say that something is a wave or a particle. Something is a wave when it oscillates through a medium. Something is a particle when it has a definite size and position at a given time in space.

Now, when photons interact with anything (say to excite an electron in an atom), they behave as if they are a particle. Because that electron has a definite position in space, to excite it, the quanta of light must hit it at that exact point.

But, when light travels through space, it does so in a wave, ie. there is an oscillation of its electric and magnetic fields. The photons are no longer like solid particles travelling through space.

Note: This explanation is from a macro perspective of what it means to be "solid" or "hit something". Also, wave-particle duality in matter is ignored.

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  • $\begingroup$ Do you really think wave-particle duality in matter is "ignored"? What about moving charge particle (like electron or proton)? You need to make it clearer for the OP, instead of putting him under more confusions. $\endgroup$ – Immortal Player Mar 19 '14 at 1:39
  • $\begingroup$ I meant I have ignored it in my explanation when I was talking about electrons getting excited by photons. $\endgroup$ – user42733 Mar 19 '14 at 11:58

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