Notebook

Notebook, 1993-

RELATIONSHIPS

[From: Light and Color, by Clarence Rainwater, Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim, Golden Press, NY, Western Publishing Company, Inc., 1971.]

Plane of Vibration


Polarized light waves are restricted in their direction of vibration. Normal light waves vibrate in an infinite number of directions perpendicular to their direction of travel. For example, in the head-on view of unpolarized light the lines a, b, c, d, and an infinite number of others are perpendicular to the ray. At a particular instant any one of them might represent the direction of the vibrations. Thus, from moment to moment, the direction of the light vibrations changes in a random fashion. When components of vibration in one direction only are present, the light is plane polarized. [p. 53]

Plane of vibration of a polarized light wave is usually unaffected in passing through a transparent material--it remains polarized in the same plane. Some optically active materials, however, rotate the plane of vibration in either a clockwise or counterclockwise direction. Quartz crystals occur in both clockwise and counterclockwise varieties. Sugar solutions are also optically active. A chemist can determine the concentration of sugar in a solution by measuring the rotation of the plane of vibration when plane-polarized light is passed through the solution. A dextrose sugar solution causes a clockwise rotation; levulose sugar, a counterclockwise one. A device for measuring the angle of rotation of the plane of vibration is called a polariscope. A sacharimeter is a polariscope used in sugar analyses. [p. 54]

[Light and Color, by Clarence Rainwater, Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim, Golden Press, NY, Western Publishing Company, Inc., 1971.]







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