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Glass and Light “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson.

Published byDella Watts Modified over 6 years ago

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Presentation on theme: "Glass and Light “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson."— Presentation transcript:

1 Glass and Light “There is no den in the wide world to hide a rogue. Commit a crime and the earth is made of glass.” —Ralph Waldo Emerson

2 Kendall/Hunt Publishing Company
Glass Analysis Students will learn: How to use the properties of reflection, refraction, and refractive index to classify glass fragments. Kendall/Hunt Publishing Company

3 Physical Characteristics
Density—mass divided by volume Refractive index (RI)—the measure of light bending due to a change in velocity when traveling from one medium to another Fractures Color Thickness Fluorescence Markings—striations, dimples, etc Kendall/Hunt Publishing Company

4 Kendall/Hunt Publishing Company
Light and Glass How can light interact with glass? Is light a wave or a particle? Kendall/Hunt Publishing Company

5 Refractive Index The refractive index (RI) is a constant for a given pair of materials. By definition the refractive index of a vacuum is 1. In practice, air makes little difference to the refraction of light with an absolute refractive index of , so the value of the absolute refractive index can be used assuming the incident light is in air. = speed of light in material 1 speed of light in material 2 Material Absolute RI Air 1.0008 Water 1.330 Glass, soda-lime 1.510 Diamond 2.417 Ruby 1.760

6 Kendall/Hunt Publishing Company
Snell’s Law Kendall/Hunt Publishing Company

7 Kendall/Hunt Publishing Company
Light acts like both a wave and a particle. Kendall/Hunt Publishing Company

8 Determination of Refractive Index
Immersion method—lower fragments into liquids whose refractive index is different. Match point—when the refractive index of the glass is equal to that of the liquid Becke line—a halo-like shadow that appears around an object immersed in a liquid. It disappears when the refractive index of the liquid matches the refractive index of the glass fragment (the match point) Kendall/Hunt Publishing Company

9 Determination of Refractive Index
The refractive index of a high boiling liquid, usually a silicone oil, changes with temperature This occurs in an apparatus called a hot stage which is attached to a microscope. Increasing the temperature allows the disappearance of the Becke line to be observed At match point, temperature is noted and refractive index of the liquid is read from a calibration chart Kendall/Hunt Publishing Company

10 Kendall/Hunt Publishing Company
The Becke Line The Becke line is a “halo” that can be seen on the inside of the glass on the left, indicating that the glass has a higher refractive index than the liquid medium. The Becke line as seen on the right is outside of the glass, indicating just the opposite. Kendall/Hunt Publishing Company

11 Kendall/Hunt Publishing Company
Refractive Index Liquid RI Glass Water 1.333 Vitreous silica 1.458 Olive oil 1.467 Headlight Glycerin 1.473 Window Castor oil 1.82 Bottle Clove oil 1.543 Optical Bromobenzene 1.560 Quartz Bromoform 1.597 Lead Cinnamon oil 1.619 Diamond 2.419 Kendall/Hunt Publishing Company

12 Kendall/Hunt Publishing Company
Becke Line Kendall/Hunt Publishing Company

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