Students can easily measure the width of a strand of their own hair with a monochromatic light source such as a laser. This inexpensive activity engages students in an application of single slit diffraction using Babinet’s principle.

1.
David
Young
and
Stadler
Shane
,
Cutnell & Johnson Physics
(
Wiley
,
2014
), Sec. 27.5
2.
Douglas
Giancoli
,
Physics Principles with Applications
(
Pearson
,
2013
), Sec. 24-5.
3.
T.
Greenslade
 Jr.
, “
Diffraction by a cat’s whisker
,”
Phys. Teach.
38
,
422
(
Oct.
2000
).
4.
Affordable lasers with on/off switches can be obtained online by purchasing laser pointers or inexpensive gun sights.
5.
Glenn
Elert
, ed.,
The Physics Factbook
, https://hypertextbook.com/facts/1999/BrianLey.shtml.
7.
Gregory
Braun
,
Dennis
Tierney
, and
Heidrun
Schmitzer
, “
How Rosalind Franklin discovered the helical structure of DNA: Experiments in diffraction
,”
Phys. Teach.
49
,
140
(
March
,
2011
).
8.
AAPT DigiKit: DNA Science. This multidisciplinary collection integrates physics, chemistry, and biology as students engage in a diffraction lab to model the work of Rosalind Franklin
. https://www.compadre.org/books/DNA.
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.