Light and Matter: Open Source Textbook by Benjamin Crowell
This free online textbook, Light and Matter, is intended for use in a "Physics for Life Science" course or for high school AP Physics. Within the "Wave Optics" chapter, you'll find great content support on diffraction. The text is readable and well supplemented with illustrations/diagrams. Topics include application of Huygen's Principle; single slit, double slit, and multiple slit diffraction; explicit guidance in the mathematics of path difference; and constructive/destructive interference. NOTE: "Wave Optics" begins on Page 911 of the book; "Diffraction" on Page 914. Homework problems w/answer key are found on pp. 929-932. This resource will open as a pdf file.
MITx Bio: The Structure of DNA
Want your students to take a deeper dive into the structural features that influence DNA function? This 6-minute video will help learners identify key components of DNA, including the chemical structure of a nucleotide, the four bases (adenine, guanine, thymine, and cytosine), nucleotide bonding processes, and the hydrogen bonds that are key in forming base pairs.
Hyperphysics: Bragg's Law
Bragg's Law defines the  fundamental mathematical relationship upon which X-ray crystallography measurement is based. Rosalind Franklin was an expert in X-ray crystallography and would've used Bragg's law to quantify the angle of scattering from an x-ray incident onto a crystal surface. This short tutorial explains the conceptual basis for Bragg's Law and provides a digital tool allowing students to use the equation to perform calculations.
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