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The title says it all: this blog features physics videos found everywhere on the web: animations, demonstrations, lectures, documentaries.
Please go here if you want to suggest other nice physics videos, and here if I mistakingly infringed your copyrights. If you understand French, you'll find a huge selection of physics videos in French in my other blog Vidéos de Physique.

Wednesday, 29 January 2014

Schlieren Optics

Demonstration of an optical technique that allows us to see small changes in the index of refraction in air. A point source of light is reflected from a concave mirror and focused onto the edge of a razor blade, which is mounted in front of the camera. Light refracted near the mirror and intercepted by the blade gives the illusion of a shadow.

Seen here are the heated gases from a candle flame and a hair dryer, helium gas, and sulfur hexafluoride gas. 

More information on our setup.

 Note that this version of the setup uses a white LED flashlight instead of an automotive light bulb.

 

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