6A65.52 - Variable Focal Length Lenses

Code Number:
Demo Title:
Variable Focal Length Lenses

The lens will work with either air or water.  Connect the lens to the syringe and make the lens more convex by pushing more air or water into the lens.  You can also make the lens concave by pulling air or water out of the lens.

  • Satoko Uchida, "A Variable Focal Length Lens Made from a Food Preservation Lid", TPT, Vol. 57, #3, Mar. 2019, p. 173.
  • Luka Vidic, Miha Kos, "Squeezing Light", TPT, Vol. 50, #9, Dec. 2012, p. 570.
  • Roger E. Malcolm, "Fluid Lenses", TPT, Vol. 27, # 8, Nov. 1989, p. 636.
  • Robert Ehrlich, "10.5 - A Water Lens", Why Toast Lands Jelly-Side Down, p. 161.
  • Robert Ehrlich, "10.6. A Rotating Water Lens", Why Toast Lands Jelly-Side Down, p. 162.

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.