Glass Quiz
10/27/2014
1. What are the two most useful physical properties of glass for
forensic comparisons?
2. _________________ glass fragments into small squares, “dices”,
with little splintering when broken.
3. Glass fracture lines that encircle the hole in the glass are known as
_____________________ fractures?
4. When glass’s elastic limit is exceeded, the first fractures develop into
radial lines on the surface of the (same,opposite) side to that of the
penetrating force.
5. In order to determine the refractive index of a small piece of glass,
the glass is submerged in different liquids and viewed under a
microscope. The appearance of a Becke line is used to determine
the refractive index (RI).
a. What is the Becke line?
b. What does the location of the Becke line tell you about the RI of the
fragment and the surrounding liquid?
6. A beam of light passes through air into a second medium at an angle
of 48°. The angle of refraction is measured at 33°. What is RI of the
medium?
7. Jared the investigator arrives at the scene of a hit and run collision.
The driver who remained at the scene reports that the windshield
or a side window of the car that struck him shattered on impact.
Jared searches the accident site and collects a large number of
fragments of tempered class. This is the only type of glass
recovered from the scene.
a. How can the glass evidence help Jared locate the vehicle?
b. Which window was likely broken?
• Which order were the bullet holes made? Justify your answer.