13 March 5 Microwaves, Polarization

Today: Quiz Results, Light as a Wave: Microwave Radiation, Polarization ,[object Object]

A blue photon has a higher energy than a green photon

Total internal reflection (TIR) only happens for a wave inside a medium with a slower speed Air glass Air glass

Total internal reflection with microwaves Introductory explanation of microwave source and detector

OK, Now a couple clicker questions to lead into next topic ,[object Object],Z X y ,[object Object],[object Object],[object Object],[object Object]

OK, Now a couple clicker questions to lead into next topic ,[object Object],Z X y ,[object Object],[object Object],[object Object],[object Object],Compression / rarefaction wave

OK, Now a couple clicker questions to lead into next topic ,[object Object],Z X y ,[object Object],[object Object],[object Object],[object Object],Rubber rope

OK, Now a couple clicker questions to lead into next topic ,[object Object],Z X y ,[object Object],[object Object],[object Object],[object Object],Rubber rope Either X, Y, or any angle in between! Transverse waves have polarization

Remember: Light is an electromagnetic wave ,[object Object],[object Object],[object Object],[object Object],[object Object],So if EM radiation is a transverse wave, can it be polarized?

EM Waves can be “linearly polarized” Similarly, a transverse wave on a rubber tube has a polarization hyperphysics.phy-astr.gsu.edu

Special materials can interact preferentially with one polarization of light vertical polarization is let through horizontal polarization is absorbed ,[object Object],[object Object],[object Object],You can find this demo from MIT on youtube: http://www.youtube.com/watch?v=nCAKQQjfOvk

Some applications of polarized light ,[object Object],[object Object],[object Object],[object Object]

How do polarized sunglasses work? The amount of light reflecting off the surface of water depends on the polarization One component reflects more than the other, So, reflected sunlight is polarized Polarized sunglasses can specifically absorb this polarization You tube: http://www.youtube.com/watch?v=jNXeNdmz92o&feature=related http://commons.wikimedia.org/wiki/File:Mudflats-polariser.jpg

So far, we have talked about linearly polarized light A trickier concept is circularly polarized light This occurs when the X and Y components are out of phase. http://www.ecs.umass.edu/ece/ece334/ece334/JavaApplets/Polarization/Polarization%20Applet.htm Circular polarization demo with laser? Specific rotation with sugar

A final application of polarized light Nerdy physics demo More cool demo: http://www.austine.com/

OK, so EM Radiation Can be Polarized ,[object Object],[object Object]

Clicker Question—Microwave Wavelength ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Microwave Radiation ,[object Object],[object Object],Wavelength (meters) Frequency (Hz) Temperature required to glow this color

A microwave oven can produce standing waves ,[object Object],[object Object],[object Object],[object Object],Marshmallows: http://www.colorado.edu/physics/2000/applets/oven.html

13 March 5 Microwaves, Polarization

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13 March 5 Microwaves, Polarization