text-only page produced automatically by LIFT Text Transcoder Skip all navigation and go to page contentSkip top navigation and go to directorate navigationSkip top navigation and go to page navigation
National Science Foundation
design element
News From the Field
For the News Media
Special Reports
Research Overviews
NSF-Wide Investments
Speeches & Lectures
NSF Current Newsletter
Multimedia Gallery
News Archive
News by Research Area
Arctic & Antarctic
Astronomy & Space
Chemistry & Materials
Earth & Environment
People & Society

Email this pagePrint this page

Press Release 06-127 - Video
Lesson in Light

David Snider describes the light-polarizing filter lesson from his course.
View Video

University of South Florida engineering professor David Snider uses light-polarizing filters to explain fundamental properties of electromagnetic radiation to his students.

Credit: University of South Florida

Back to article

Video Transcript:

We went outdoors and we looked at a section of the sky in which sunlight comes bouncing off of the air molecules  the blue light  and it's un-polarized. And to illustrate the principles of the polarizing filter, we hold the polarizing filter up which just passes about half of the light which is un-polarized. And then we take a second polarization filter and if it's aligned with the first one, nothing happens; but if you turn it 90 degrees, then none of the light that the first filter polarizes gets through the second filter and so it turns black altogether. And so I had the students take away and just use one polarizing filter and see if they could find certain sky directions where they could completely blacken out the sky. And these actually happen when you're observing at 90 degrees to the sun. We tried to show this as well with the camera pointing at that direction and using a single filter.

Related media icon
This video requires the free RealPlayer plug-in


Email this pagePrint this page
Back to Top of page