Water is more elastic than air. why?

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue