Code Number: 7A60.25

Demo Title: X-ray Diffraction - DNA Analog

Condition: Good

Principle: Crystal Structures, DNA models

Area of Study: Optics, Modern Physics

Equipment:

Helium-neon laser (2 to 5 mw.) or Laser Pointer, Optics bench, Small Springs such as from a ball point pen, optional saw tooth pattern.

Procedure:

Shine the slightly diffused laser onto the side of the spring. A diffraction pattern such as that of a typical DNA molecule will be produced.

You may also make or use a small saw tooth pattern to produce a similar pattern.

References:

Jin Tao, Rubing Zhou, Yang Zhiqiang, Qian Cheng, Xingfeng Zhu, "Problem-Based Learning via X-Shaped Diffraction patterns Using Everyday Objects", TPT, Vol. 63, #12 Dec. 2025, p. 757.

Disclaimer

These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist. The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose. The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources. Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks. These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage. Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.

Instructional Resources and Lecture Demonstrations

7A60.25 - X-ray Diffraction Patterns - DNA Analog

Disclaimer