(adsbygoogle = window.adsbygoogle || []).push({}); The given problem:

What is the focal length of a Plano-convex lens, assuming parallel rays of light from s=∞ is traveling from the flat end of the lens. The lens is a glass hemisphere of radius R. Additionally the index of refraction of glass is higher than that of air.

2. Relevant equations

General lens maker equation:

ng/s +nair/s' = (ng + nair)/R

==> assuming s=∞; s'=R/(ng-nair)

3. The attempt at a solution

I do not know if the distance to the focal point (i.e., the focal length s', as s=∞) is the distance starting FROM the point where the light hits the lens, or where the light exits the lens?

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Focal Length of a Plano-convex Lens

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