Elementary treatise on physics experimental and applied

by Adolphe Ganot

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1875 ...the converging meniscus, and he lens F the diverging meniscus. Fig. 394 The first three, which are thicker at the centre than at the borders, are verging; the others, which are thinner in the centre, are diverging. a the first group, the double convex lens only need be considered, and n the second the double concave, as the properties of each of these lenses ipply to all those of the same group. In lenses whose two surfaces are spherical, the centres for these surfaces it called centres of curvature, and the right line which passes through hue two centres is the principal axis. In a plano-concave or planoonvex lens, the principal axis is the perpendicular let fall from the the spherical face on the plane face. In order to compare the path of a luminous ray in a lens with that in prism, the same hypothesis is made as for curved mirrors (483), that is, iie surfaces of these lenses are supposed to be formed of an infinity of mall plane surfaces or elements; the normal at any point is then the erpendicular to the plane of the corresponding element. It is a geometrical principle that all the normals to the same spherical surface pass trough its centre. On the above hypothesis we can always conceive two Une surfaces at the points of incidence and convergence, which are inIjied to each other, and thus produce the effect of a prism. Pursuing lis comparison, the three lenses A, B, and C may be compared to a cession of prisms having their summits outwards, and the lenses D, and F to a series having their summits inwards; from this we see at the first ought to condense the rays, and the latter to disperse them, "we have already seen that when a luminous ray traverses a prism it deflected towards the base (502). 510. Foci In doable convex lenses.--The focu...

350 pages, Paperback

Published January 1, 2012