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 ...

In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.

Coleman and Howitt 1 have observed the interesting fact that if one dissolves denatured silk-fibroin in cupriethylene-diamine, a product is obtained which does not differ essentially from the native ...