Astudent remarks that the relationship of ray optics to the more general wave picture is analogous to the relationship of newtonian mechanics, with well - defined particle trajectories, to quantum mechanics. comment on this remark.

How do you measure the thickness of paper?Because the same size sheet is always being weighed, GSM (grams per square meter) provides a more uniform scale to judge a paper's weight and thickness. Finally, you can always measure the thickness of a sheet of paper using a caliper. Specialty media is often specified in Points or 1/1000 of an inch.