Apaperweight is made of a solid glass hemisphere of index of refraction 1.55. the radius of the circular cross section is 5.0 cm. the hemisphere is placed on its flat surface, with the center directly over a 1.5 mm long line drawn on a sheet of paper. what length of line is seen by someone looking vertically down on the hemisphere?

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -