Activity 1: Which sunglasses for a summer by the lake?




Activity summary

What you must remember :
  • polarization
  • reflection
Skills linked to the curriculum:

Compétences Capacités à maîtriser
APP

Extraire les informations jugées pertinentes concernant la polarisation de la lumière et les effets d’un filtre polarisant.
COM Utiliser un vocabulaire scientifique adapté.
Présenter des résultats.


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Documents

Document 1: polarization by reflection


Unpolarized light can undergo polarization by reflection off of nonmetallic surfaces. The extent to which polarization occurs is dependent upon the angle at which the light approaches the surface and upon the material that the surface is made of. Metallic surfaces reflect light with a variety of vibrational directions; such reflected light is unpolarized. However, nonmetallic surfaces such as asphalt roadways, snowfields and water reflect light such that there is a large concentration of vibrations in a plane parallel to the reflecting surface. A person viewing objects by means of light reflected off of nonmetallic surfaces will often perceive a glare if the extent of polarization is large. Fishermen are familiar with this glare since it prevents them from seeing fish that lie below the water. Light reflected off a lake is partially polarized in a direction parallel to the water's surface. Fishermen know that the use of glare-reducing sunglasses with the proper polarization axis allows for the blocking of this partially polarized light. By blocking the plane-polarized light, the glare is reduced and the fisherman can more easily see fish located under the water.

Source: https://www.physicsclassroom.com/class/light/Lesson-1/Polarization




Problem: choosing your summer glasses
Identify the pair of glasses that is capable of eliminating the glare resulting from sunlight reflecting off the calm waters of a lake? (The polarization axes are shown by the straight lines.)



Last modified: Sunday, 3 February 2019, 2:51 PM