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If light cannot bend, then how magnify glass works?

  1. Dec 14, 2014 #1
    i don't understand if light cannot bend, then how magnify glass works?
    how it is bending & magnifying the light?
     
  2. jcsd
  3. Dec 14, 2014 #2

    phinds

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    Google refraction.
     
  4. Dec 14, 2014 #3
    if light cannot bend then how refraction & reflection of light are working?
    is it still mystery or any other theory is there for this?
     
  5. Dec 14, 2014 #4

    phinds

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    There is nothing "mysterious" about it at all. GOOGLE REFRACTION and read the whole thing.
     
  6. Dec 14, 2014 #5
    i am asking if light can not bend, how REFRACTION is done ?
     
  7. Dec 14, 2014 #6

    Dale

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    Who says a ray of light does not bend?
     
  8. Dec 14, 2014 #7
    how medium can bend the light?
    water is bending the light everytime. is it mystery?
     
  9. Dec 14, 2014 #8

    Dale

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    It is not a mystery. Refraction is caused by a change in the speed of light at the interface of two different transparent media.
     
  10. Dec 14, 2014 #9
    if we throw the ball it will bounce, when it touches the ground, so same way, the light bounces back that bounce of light is called refraction, am i right?
     
  11. Dec 14, 2014 #10

    Dale

    Staff: Mentor

    That is reflection. Reflection and refraction are different.

    If you want a mechanical analog of refraction think of a vehicle which rolls at an oblique angle from a smooth road onto a rough road.
     
  12. Dec 14, 2014 #11
    think of a vehicle which rolls at an oblique angle: means vehicle going down mountain slope down, then it will go fast, because slope down will increase the velocity of vehicle. same way refraction will increase the speed of light ray like speed of vehicle increased by mountain slope through mechanical analogy.
     
  13. Dec 14, 2014 #12

    Dale

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    Forget the slope of the mountain, consider the road to be level. What happens when a vehicle rolls from a smooth road onto a rough road?
     
  14. Dec 14, 2014 #13
    of course any two wheeler or four wheeler vehicle will get spoiled, due to rough end due to heavy friction. sorry, but it doesn't explains about light.As you said it will bend due to different medium, wiki is showing light bend due to surface phenomenon, i am confused. so light bends because of two reasons: surface phenomenon & different medium? what i understand about light bend is right or wrong?
     
    Last edited: Dec 14, 2014
  15. Dec 14, 2014 #14

    Dale

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    OK, now, before it gets spoiled, will it travel straight or will it tend to turn one direction or the other?

    Of course it doesn't explain, it is an analogy, not an explanation. The explanation is Maxwells equations.
     
  16. Dec 14, 2014 #15
    will it travel straight or will it tend to turn one direction or the other? it depends on driver's experience. of course anybody can change vehicle direction due to steering. it works under steering gear mechanism. but light is electromagnetic waves. it carries energy every time.
    vehicle direction is depends on driver mindset.
    so due to Maxwells equations, light is bending & bounces back?
     
    Last edited: Dec 14, 2014
  17. Dec 14, 2014 #16

    Dale

    Staff: Mentor

    No. The tendency of the vehicle is a matter of physics. An experienced driver can compensate for what the vehicle tends to do, but that does not change the physics.

    Again, what does the vehicle tend to do?
     
  18. Dec 14, 2014 #17

    Dale

    Staff: Mentor

    It seems like you have left for the time being, and in an hour or so I will have to also, so I will answer my own question and then give an explanation from Maxwells equations.

    If there is rough road to the right and a vehicle goes from smooth road onto the rough road then it will tend to pull to the right. This will happen as soon as the right tire hits the rough road and is slowed down compared to the left tire which is still going on the smooth road. Analogously, light will turn if it goes into a medium with a slow speed of light (analogous to the rough road).

    One of the simplest solutions to Maxwells equations is a single frequency plane wave. If you take two such solutions, one for each material, and match them at the interface, then you will get that the propagation direction is different in each.
     
  19. Dec 14, 2014 #18
    thank you it explains lot, but what i understand is there is no theory to explain or demonstrate why light refraction & reflection.
     
  20. Dec 14, 2014 #19

    Dale

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    I already told you that the theory is Maxwells equations.
     
  21. Dec 14, 2014 #20

    Drakkith

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    Let's do away with analogies here, I don't think they will help. Light is NOT a ray that travels in a straight line. It is an electromagnetic wave. A ray is a simplification that makes it easier to calculate what the light will do in certain situations, such as what happens when it enters a lens or hits a mirror.

    Refraction is a property that all types of waves have. When a wave enters a medium where the speed of the wave is different, it changes direction unless it enters the new medium straight on at a 90 degree angle. The reason why this happens is hard to grasp but has to do with how different parts of the wave interfere with each other while the wave moves across the boundary.

    I have no idea why you believe this. It is utterly wrong. Refraction and reflection are understood extremely well.
     
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