The Physics Factbook™
Edited by Glenn Elert -- Written by his students
An educational, Fair Use website
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|Piezo Technology. Epson (UK) Ltd.||"45 microns, 2 times smaller than the diameter of a human hair and close to the limit of resolution for the human eye"||90 µm|
|Denny R's Homepage. Denny & Gayle Rossbach. Palmdale, CA.||"Diameter of a human hair
inches: 0.001; centimeters: 0.00254"
|Why Choose a Water Treatment System? Aqua-Fresh Drinking Water Systems, Inc.||"Particulate contaminants including asbestos, rust, sediment, dirt, and scale as small as 0.2 microns (1/300th diameter of a human hair)."||60 µm|
|Hair - Important Facts About Hair. CAQTI Cosmetics, Inc.||"Flaxen hair is the finest, from 1/1500 to 1/500 of an inch in diameter … and black hair is the coarsest, from 1/450 to 1/140 of an inch."||17–50 µm
Hair can be found all over human body, except for the palms of hands and at the soles of feet. The purpose of hair is protective: the hairs on the body keeps a person warm, nose hairs prevent dust and dirt from entering the respiratory system, and eyebrows prevent sweat from entering the eyes.
The diameter of a human hair does not have a standard value since different people have different hair structures. Your genetic makeup can cause the width of your hair to differ from that of other people. Hair color is also a big factor. Black hair is thicker than is red hair. The weather can also affect the diameter of a hair strand. As the weather gets warmer, the diameter of body hair increases. Age is another factor. Babies and young children have finer hair than adults. As a person grows up, their hair becomes thicker and stronger. Another factor is that, the closer to the root of the hair, the thicker a strand of hair would be.
In my research, I have found the diameter of human hair to range from 17 to 181 µm (millionths of a meter).
Brian Ley -- 1999
|SEM image of the week: Only their hairdresser knows for sure. Mert Keçeli, Joanne Wen, Sara Saad, Glenn Elert. Midwood Science (7 November 2011).||[see images below]||60~80 µm|
|Student 1: 77 µm||Student 2: 60 µm||Student 2: 68 µm||Student 3: 71 µm|
Editor's Supplement -- 2011
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