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Optics

Blazing goIITian

Joined:	9 Mar 2008
Post:	592

10 Oct 2008 20:57:29 IST

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637

glass lens.......rates assured..

None

why do a glass lens have radius of curvature equal 2 its focal length!!

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satyam

New kid on the Block

Joined: 12 Aug 2008

Posts: 19

10 Oct 2008 21:03:01 IST

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dude .............the lens involves 2 spheres whose radius are same .........radius=focal length......diameter=curvature length........................please rate me

bharat goswami

Blazing goIITian

Joined: 9 Mar 2008

Posts: 592

10 Oct 2008 21:08:33 IST

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yaar ab tak jitni optics mere demaag mei ghusi hai uske hisab se focal length is half of the radius of curvature...

there is something i m lackin..

give some gud explanations...

harsh

Scorching goIITian

Joined: 3 May 2008

Posts: 288

10 Oct 2008 23:32:11 IST

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@sngh_stym....

hey is it tht lens always contain 2 spheres of same radius????i don't thnk so...it may or may nt contain 2 spheres of same radiusi.i radius can be diiferbt too.......

islahul

Cool goIITian

Joined: 28 Apr 2008

Posts: 58

12 Oct 2008 17:36:41 IST

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first of all there is no centre or curvature in case of lenses!! dont confuse with R1 and R2 in lens maker formula!!
C isnt valid for lenses due to some principal axis assumptions which is not there in case of (paraxial rays)mirrors.
the relation f=C/2 is only for mirror in paraxial cases.
for lenses take f and 2f in place of C(which actuly dosnt exist for lenses). that is correct!! i am cent sure in my answer!!

vignesh the cooler version of newton

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Joined: 16 Mar 2008

Posts: 1801

12 Oct 2008 19:43:42 IST

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hey hey....
wait....
who said radius of curvature is 2 times focus of lens.....
it is only for mirrors...
focal lens depends on relative refractive index, radius of curvature of both the sides of the mirror.....
plzz tell me if i'm wrong..

srinath

Scorching goIITian

Joined: 24 Jan 2008

Posts: 266

13 Oct 2008 09:42:01 IST

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@littlebrother91 , whatever you said is true IFF , the surrounding medium is air.

actually , by lens makers formula.

So , It depends on both the R.I of the medium surrounding the lens as well the R.I of the material of the lens n_m- R.I of the material of lens . n_s - R.I of surroundign medium . so when n_m=1.5 and n_s =1 . we ahave f=R . It's n_s not n_o.

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