Experimental Measurement of the Diameter of a Human Hair via Two-Color Light Diffraction

Abstract

The width of a human hair sourced from a female elementary school student was measured by light diffraction using red and blue laser pointers. The two laser sources both provided consistent estimates of the hair diameter of approximately 50 μm. The overall experiment and writing process provided a temporary respite from COVID-19 shelter-in-place requirements and deteriorating spring weather that precluded outdoor activities.

Acknowledgments

We acknowledge Northwestern University for salary support and Amazon.com for providing excess cardboard boxes used in this study.

Author contributions

Cecilia Dichtel compiled building materials, sourced the human hair, built the test setup, and drew the Table of Contents image. June Dichtel joined the team when the experiments appeared “cool” and she had finished reading a book. She aligned the lasers and measured the interference minima. William Dichtel poorly articulated the wave nature of light and the concept of diffraction to the other authors. All authors wrote the manuscript.

Disclosure statement

The authors are related to the Managing Editor of the journal, however the Managing Editor was not involved in any part of the editorial decision-making process which led to acceptance of the paper for publication.