SCREENING and spin doublets in X-ray spectra are matters of great significance. The formation of these doublets in X-ray diagram lines is now well known and has received satisfactory theoretical ...

Draw a ray from the object to the lens that is parallel to the principal axis. Once through the lens, the ray should pass through the principal focus. Draw a ray which passes from the object through ...

OWING to a number of unforeseen circumstances, mostly beyond our control, an incorrect version of part of our communication under the above title was printed in Nature of December 22, 1951. Our main ...

When light moves from air into glass or plastic it is refracted close refractionProcess by which a wave changes speed and sometimes direction upon entering a denser or less dense medium, eg a light ...