Chapter 14 Flashcards

1
Q

Paint as physical evidence is most frequently encountered in what types of crime?

A

Hit-and-run.

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2
Q

What can the PDQ database help determine about a vehicle when paint chips are recovered?

A

The make, model, and year of the vehicle.

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3
Q

What is paint composed of?

A

Paint is made of pigments, binder, and solvents.

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4
Q

What is the role of the electrocoat primer on cars?

A

: Provides corrosion resistance.

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5
Q

What is the role of the primer surfacer on cars?

A

Smooths out imperfections and enhances adhesion of the basecoat.

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6
Q

What is the role of the basecoat on cars?

A

Provides the color and aesthetic appeal of the vehicle.

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7
Q

What is the role of the clearcoat on cars?

A

Adds protection and a glossy finish.

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8
Q

Which property of paint imparts it with its most distinctive forensic characteristics?

A

The layer structure.

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9
Q

What is the main ingredient in ordinary glass?

A

Sand (silicon dioxide).

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10
Q

Where is tempered glass used?

A

In car side windows/for protection.

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11
Q

What does flotation determine about a particle of glass?

A

Its density.

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12
Q

Describe radial cracks in glass.

A

Cracks that extend outward from the point of impact.

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13
Q

Describe concentric cracks in glass.

A

Cracks that form in a circular pattern around the point of impact.

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14
Q

What are the two most important physical properties of glass for forensic comparisons?

A

Density and refractive index.

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15
Q

What does the larger opening of a crater-shaped hole in glass indicate?

A

The exit side of the projectile.

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16
Q

If broken glass cannot be physically pieced together, what characteristics should be compared?

A

Density and refractive index.

17
Q

How is the refractive index of a medium determined?

A

By the ratio of the speed of light in a vacuum to the speed of light in the medium.

18
Q

How should glass evidence be collected and packaged?

A

Collect all visible fragments.
Package in rigid containers to avoid further breakage.
Label each fragment by location.

19
Q

How should paint chips be collected and packaged?

A

Use tweezers or a clean sheet of paper.
Package in sealed containers (e.g., vials, paper folds).

20
Q

How should soil evidence be collected and packaged?

A

Collect samples in airtight containers.
Prevent cross-contamination by using separate containers.

21
Q

How much soil is needed for comparison?

A

Approximately 1 to 2 tablespoons.

22
Q

At what distance should various soil samples be collected?

A

Within a 100-yard radius of the crime scene.