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Author Topic: Why doesn't a laser beam refract?  (Read 2132 times)

Offline annie123

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Why doesn't a laser beam refract?
« on: 03/04/2014 22:19:09 »
I have a small pen with a laser beam in it. I thought the beam would bend when I passed it through water but I didn't even see the beam go through the water, just appear on the other side of the glass. Why is this?


 

Offline JP

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Re: Why doesn't a laser beam refract?
« Reply #1 on: 03/04/2014 22:22:33 »
Water and glass?  What are you sending it through? 
 

Offline dlorde

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Re: Why doesn't a laser beam refract?
« Reply #2 on: 04/04/2014 00:33:02 »
Did you point it at an angle to the surface? are you certain it came out directly opposite where it went in, not offset?
 

Offline annie123

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Re: Why doesn't a laser beam refract?
« Reply #3 on: 04/04/2014 02:04:21 »
I shone it through a glass of water horizontally, parallel to the surface on which the glass stood.I measured the height above the surface  for the input and output. They were the same. I also tried shining the light at an angle of about 45* and it went directly through  the glass without bending. And why don't I see the light go through the water, or through the air as one would with ordinary light beams?
 

Offline JP

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Re: Why doesn't a laser beam refract?
« Reply #4 on: 04/04/2014 02:58:34 »
Try putting the light horizontal (parallel to the table on which the glass stands) and move it sideways so it hits the edge of the glass.  It should bend inwards as the glass full of water will act like a lens.  I can't quite visualize the setup you have (45 degrees with respect to what?) but I can assure you that if you do this experiment, you'll see the light coming out at a different angle than it entered the glass. 

As for why you don't see it--the only reason you see a laser at all is that it has bounced off something and that scattered light gets to your eye.  A laser traveling through a vacuum will be completely invisible to you unless you put your eye right in its path.  In air, there's lots of dust particles and so the beam scatters a lot so it is easily visible.  I'm guessing you're using pretty clean water, so there's little to scatter off of.  Try dropping some chalk dust in and you'll be able to see the laser beam. 
 

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Re: Why doesn't a laser beam refract?
« Reply #4 on: 04/04/2014 02:58:34 »

 

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