PURPOSE: To demonstrate the polarization of light.
DESCRIPTION: Two polaroids are placed on the overhead. Light
transmitted from the overhead passes through one polaroid to become polarized. By
rotating a second polaroid through an angle of 360 degrees the effect of the polarization
can be seen as the transmitted, polarized light will become alternately brighter, when the
two polaroids are aligned, and dimmer when the two polaroids are crossed. This is
shown in the two photos above.
When the bottom polaroid has its plane of polarization oriented parallel
with the second polaroid all the light is seen to be transmitted brightly through the two
filters, as shown in the photo above left. By rotating the angle of polarization,
the plane of polarization between the two polaroids acn be crossed and they become dark,
as no light is transmitted. This is shown in the above right photo.
EQUIPMENT: Two Polaroids mounted in rotator.
SETUP TIME: None.
NOTES:
HN38 Polarizer sheet material. It is 0.030" thick.
The 3M company makes a popular Polaroid sheet material called XP38 Polarizer.
Edmund Scientific sells Polarizer sheets:
http://scientificsonline.com/product.asp?pn=3071939&bhcd2=1149272125
And I think Sargent Welch sells it, too?
There is a company called Rosco, Google "Rosco
Linear Polarizing Filter Roscolux".
http://polarization.com/shop/catalog/index.html
also,
http://www.3dlens.com/shop/polarizer.php
Read this TPT article
"Transmission through crossed Polaroid filters"
by Don Easton
Phys. Teach. 39, 231 (20)
Updated by JZ in 6/02/2006