Excerpt from Scattering From a Penetrable Sphere at High FrequenciesWe consider a scalar plane wave incident on a penetrable sphere in the limit of high frequencies for which the wave length of the incident wave is small compared to the radius of the Sphere. Quantum mechanically, the prob lem represents the scattering of a highly energetic particle by an attractive square well. It is also closely related to the corresponding electromagnetic problem which occurs in the scattering of light by water droplets. As such, it has engaged the attention of very many scientists whom we can not hope to enumerate here. A.more or less complete historical record of the contributors to the raindrop prdblem.may be found in van de Hulst's book [i]. The justifi cation of the present work lies in the new representation of the scattering amplitude which is particularly appropriate to the study of it in the high frequency or short wave length limit. By means of it, it is possible to dis tinguish the contributions of the geometric optics field and of the diffracted field.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.