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Ratio of a ray of light with a refracted ray

Hey sum1 please tell me that :

if d1=Ray of light through a glass slab(dotted line ie extension of unrefracted ray)


and if d2=Refracted ray

is d1/d2=mu(refractive index)
 

Answers and Replies

jtbell
Mentor
15,402
3,190
How do you divide two light rays? What kind of quantity are [itex]d_1[/itex] and [itex]d_2[/itex]? Angle, distance, wavelength, whatever? :confused:
 
d1 is the length of the unrefracted ray(extension of the incident ray into the glass slab) .d2 is the length of refracted ray
 
Please help!
 
39
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Friend ! u r saying that what's the ratio of lengths of rays - the extended incident one and the refracted one......in normal diagram u join the initial rays such that triangle formed by normal & inc. ext. =~ triangle by normal & incident(initial) ray.....now....apply geo. u get d1/d2 =sin(90-r) / sin(90-i) which is not equal to mu...as angles formed are i & r & not their complements....
 
ofcourse i kno that.....but thats wat happens when u do it experimentally
 
39
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I am sure the angles u took in experiments was pi/4..45....and students often take it....
 
Well no...this was in two different cases
 
38
0
Length of a ray? How do you define that?
 
Well.....if u sketch the path of light...and then measure the length it covered
before exiting the slab
 
38
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So they are not true.

Call h be the thickness of the slab, then

d1=h/cosi
d2=h/cosr

where i and r are initial and refraction angles

It's clear that d1/d2=cosr/cosi, while n=sini/sinr

They are equal only if sinrcosr=sinicosi or i+r=90 degrees

or tani=n

Just true at Brewster angle!
 
Last edited:

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