The size/diameter of our human hair is very tiny, around 10-100 μm. In other words, a regular #2 pencil is about equivalent in size to a bunch of over 10 thousand hairs!!! To measure such a tiny thing, most of regular tools don’t help at all! However, spectroscopy can do a fantastic job here! What we need are a portable laser generator, a used CD disk (or something similar) as the holder of hair, some tapes, a platform with adjustable height, and a screen (or just a white wall). Shine the laser beam on the hair at the center of CD, do some measurements using a regular ruler/a measuring tape, and use some basic geometry/trigonometry to find the size of a hair of anyone (yourself? a friend?). Enjoy the pretty diffraction pattern on the screen:)
