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Homework Help: Partial Reflection-Partial Refraction

  1. Jan 4, 2012 #1
    1. The problem statement, all variables and given/known data

    Can partial reflection-partial refraction occur with all waves (ie. other than light)?

    2. Relevant equations

    3. The attempt at a solution

    My textbook constantly refers to light and apparently so does Google.

    "For still larger incident angles there is no refraction at all,with all the wave energy being reflected; this behaviour of light is referred to as total internal reflection. This phenomenon is analogous to the total internal reflection of light."

    First it says that the behavior of light is referred to as total internal reflection and then it says it is analogous to the total internal reflection of light, so it seems that it can apply to all kinds of waves. Also, this chapter of my textbook is not specifically for light, its just a general introduction to waves in two dimensions.
  2. jcsd
  3. Jan 4, 2012 #2

    Simon Bridge

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    Try it out with water waves :)
    (To get two "refractive indexes", change the depth of the water sharply at the "boundary".)

    [edit] I did a reality check on how easy it would be to google for this, and it took several attempts, so I decided to just show it to you...
    See below:
    http://www.thephysicslaboratory.org/Essays_Unit_2/Wave_Tank_2.1_files/Refraction.jpg [Broken]
    ... here water waves are moving from shallow to deep water - you can clearly see the refraction,
    but if you look carefully you can also see the faint reflected waves as they interfere with the incoming ones, giving it a cross-hatched look.

    [Everything looks wobbly because of the refraction of light in the water - the photographer would have done better with a darker room and a strobe-light mounted close to the water - a darker lower surface to the tank would help too.]
    http://www.thephysicslaboratory.org/Essays_Unit_2/Wave_Tank_2.1.html [Broken]

    You can also see it in waves on a spring - though it's clearer with pulses - this time use a heavy and a light slinky and send a pulse from the light to the heavy end - you get an inverted reflected pulse, and a small transmitted pulse.
    Last edited by a moderator: May 5, 2017
  4. Jan 5, 2012 #3
    Ok Thank You!

    Also, does total internal reflection only apply to light?
  5. Jan 6, 2012 #4

    Simon Bridge

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    All the wave phenomena apply to anything with wave-like properties. Which would be everything (with the possible exception of cats - ask Schodinger...)

    You can also do lenses, prisms etc.
    There are differences, water does not have particle-like properties while light can.
    You can also get waves of probability which gets really interesting.

    Have a play with a ripple-tank like in the pic ... or just draw the rays on the pic and you'll be able to work out the critical angle for total internal reflection. (I think the frequency of the waves and the scale is in the source page.) It's just geometry... you know how total internal reflection works right?

    Hmmm ... unable to find pics of this.
    In general, there seems to be a lack of this sort of photo online... looks like I may have a summer project.
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