A short-sighted patient has a far point of : without correction

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging

Optics and Photonics, Ch Stops, pupils and optical instruments

Problem

A short-sighted patient has a far point of

40\ \text{cm}

: without correction, distant objects cannot be brought into focus, but an image formed

40\ \text{cm}

in front of the eye can be. A thin spectacle lens is to be ground from crown glass (

n = 1.5

) with its first surface of radius

R_1 = +20\ \text{cm}

(Chapter 1 sign convention:

R > 0

when the centre of curvature lies to the right of the vertex). ((a)) Find the dioptric power the spectacle lens must have. ((b)) Using the Chapter 1 lensmaker's equation, find the radius of curvature

R_2

of the second surface needed to give this power.

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