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**Kurre****Member**- Registered: 2006-07-18
- Posts: 280

here is a math/physics problem or exercise that i made:p

You have a disc made of glass formed as shown in the picture. The edge of the disc is described by the function 4 - x².

a light beam is launched straight down at the point (x,f(x)) where it is refracted and hits the X-axle.

Your task is to describe how the distance a depends on the distance x, in other words the function a(x)

the law of refraction is:

where V1 is the angle of incidence, V2 the angle of refraction and N1 is the refractive index for air (1) and N2 is the refractive index for glass (1,52)

i will post my solution later

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**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

awww. doesnt work ah well, atleast i tried

*Last edited by luca-deltodesco (2007-02-12 08:48:46)*

The Beginning Of All Things To End.

The End Of All Things To Come.

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**luca-deltodesco****Member**- Registered: 2006-05-05
- Posts: 1,470

actually. when refraction occurs, the refracted ray is in the opposing side of the normal, so r is negative to what i have above, and plugging that in, it does seem to work.

http://denvish.net/ulf/1171313711_grah.php

*Last edited by luca-deltodesco (2007-02-12 08:55:21)*

The Beginning Of All Things To End.

The End Of All Things To Come.

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**Kurre****Member**- Registered: 2006-07-18
- Posts: 280

nicely done, and cool "animation"

i think I got the same graph as you, altough my function is way different from your..interesting

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,663

Yeah, neat animation, luca, as always

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Kurre****Member**- Registered: 2006-07-18
- Posts: 280

Here is my solution:

the derivative of the function will be the same as -tan for the corner in the tangent, since

(its negative since the curve is going down)

V being the angle in the corner of the triangle that the function for the tangent in (x,f(x)) creates.

V will be the same as the angle of incidence

(see picture)

B=angle of refraction

i think it works, it is maybe possible to short it down

*Last edited by Kurre (2007-02-16 06:39:08)*

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