forensics chapter 15 (glass evidence)

amorphous

without fixed shape or form; when applied to a solid, atoms arranged randomly.

backscatter

fragments of glass left on the entrance side of an impact

becke line

a halo-like ring that appears around the edge of glass when placed in a liquid medium with a refractive index that differs from the refractive index of the glass

bullet resistant glass

a laminated and tempered glass composed of two layers

concentric fracture

circular pattern of cracks that forms around a point of impact

conchoidal fractures

the curved radial glass fracture marks located on the edge of glass

density

the ratio of the mass of a substance to the volume of the substance

glass

a hard, transparent, amorphous, brittle solid made by heating a mixture of silica and other materials

laminated glass

a double layer of glass held together by a middle layer of polyvinyl butyral (plastic); a type of safety glass used for windshields

lead glass (crystal)

glass containing lead oxide

radial fracture

pattern of cracks that move outward from a point of impact

refraction

the change in the direction of light as it changes speed when moving from one substance into another

refraction index

a measure of how light bends as it passes from one substance to another

silicon dioxide (SiO2)

the chemical name for silica (ingredient in glass)

tempered glass

heat or chemically treated safety glass that breaks forming very small pieces

glass evidence

glass contains valuable evidence about a projectile. Hair or blood may be on the fragmented glass giving evidence to what really happened.

glass is

Class evidence

colored glass

adding different metal oxides to glass can alter its color.

density equation

D=mass/volume

refraction

the change in the direction of light as it passes from one medium to another.