Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Medium of light

  1. Mar 9, 2005 #1
    new to the forums, had a question and thought someone might have an answer. If I remember from high school physics, in order for a wave to occur it must pass through a medium i.e.. sound through air, waves through water. my question is what do light waves use as there medium as they can travel through the vacuum of space. thanks for your time.
     
  2. jcsd
  3. Mar 9, 2005 #2

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    They don't.WAVES NEED SOURCES.Incidentally,light waves do not need support medium...Who told u that waves need a medium (substance:matter) to propagate,was not referring to light.If he was,he was wrong.

    Daniel.
     
  4. Mar 9, 2005 #3
    when we were learning about waves in grade 11 physics, our teacher said that waves needed a medium to propagate. I guess this kind of answers my question, but if light does not need any type medium to propagate, then is light waves in the same sense as sound waves or waves in water?
     
  5. Mar 9, 2005 #4

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Nope,it's a special type of wave.It's the kind of wave that propagates in vacuum...It's a transversal wave.

    Daniel.
     
  6. Mar 9, 2005 #5
    so, let me get this right. light has to be made up of particles in order for it to be a transversal wave. so would it be right to say that the wave of light itself is the medium?
     
  7. Mar 9, 2005 #6

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Not necessarily.It's a coincidence that LIGHT is made up of photons which have ONLY transversal degrees of freedom.As for the secod part,let's call light LIGHT,okay...?It's not a medium for anything.

    Daniel.
     
  8. Mar 9, 2005 #7
    Okay, i wasn't thinking of light as a medium, i was thinking of the light as a wave in the same sense as my previous examples. i am just trying to make sense of how light can travel through a vacuum. I guess my question would be how does light travel if it does not need a medium to travel on.
     
  9. Mar 9, 2005 #8

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    At classical (macroscopical) level light is made up of magnetic & electric field.The existance & the propagation concepts are independent of the "environment",whether vacuum,or not.

    Daniel.
     
  10. Mar 10, 2005 #9
    The answer to "how light waves travel" is "by electromagnetic induction". They don't call them electromagnetic waves for nothing, they are periodic oscillations in the electromagnetic field.

    If somebody asks me "what is waving in a light wave?" I give them the unambiguous answer "It is an electromagnetic field".
     
  11. Mar 10, 2005 #10
    tech by trade

    First let me be clear that dextercioby is absolutely correct. But I think that for clarity it would be good for you to understand that the distinction dex is making is of major importance only in the realm of Relativity. In other words where you would swich from using Newtonian to Einsteinian physics. Most real world calculations treat light if it were a wave traveling through a medium. Conceptually, it is convenient to think of it that way _as long as you understand it is not actually true_.
     
  12. Mar 10, 2005 #11
    thanks, its starting to make some sense. i think more research is needed on my part.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Medium of light
  1. Light and mediums (Replies: 14)

Loading...