Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
, being normal to the sphere, passes through it withoutdeviation. The point where A and B meet is the/ocws for parallel rays. To find the distance of the focus from the centre of the lens, divide •238 OPTICS. the index of refraction, of the material of whicli the lens is made, bytwice its excess… … curvature of the several lenses in the diagram, are the centres of thetwo circles. The axis of the lens is the straight line drawn through the centresof curvature, as LM, for the lens H. In higher optics, it is demonstrated that there is always one point onthe axis of a lens, such, that rays of…
Physics · Astronomy
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