Refractive Index & Light Examination Deck (Exam 1)

Question 1

This concept is the ratio of the speed of light in a vacuum (c) to the speed of light in a certain medium (v).

Answer 1

What is refractive index (n)?

Question 2

Why is the refractive index always greater than 1?

Answer 2

Nothing is greater than the speed of light

Question 3

Why is temperature inversely proportional to refractive index and density (HINT: v = lambda * frequency f)?

Answer 3

Higher temperature = higher speed of light in medium = lower refractive index = less density

Question 4

Is the Becke Line test quantitative or qualitative?

Answer 4

Qualitative

Question 5

How do you determine the results of the Becke Line test/method?

Answer 5

An object is submerged in reference oil with a known refractive index, and the “halo” created goes to the medium with a greater refractive index

Question 6

What happens to the halo in the Becke Line test when the refractive indices of the reference and evidence are the same?

Answer 6

The halo disappears

Question 7

What is the difference between photoluminescence and chemiluminescence?

Answer 7

Photoluminescence’s glow is triggered by light and light absorption while chemiluminescence’s glow is triggered by a chemical reaction

Question 8

What are some examples of uses for photoluminescence?

Answer 8

Neon and fluorescent lamps

Question 9

What are some examples of uses for chemiluminescence?

Answer 9

Luminol and BlueStar for semen, saliva, etc.

Question 10

What is a common approach to fingermark detection on nonporous surfaces such as glass, metal, and polymers?

Answer 10

Powder

Question 11

What is another common approach (besides powder) to fingerprints on nonporous surfaces?

Answer 11

Cyanoacrylate, or super glue, fuming

Question 12

This technique can be used to follow up cyanoacrylate fuming when there is background interference and you are having trouble determining the ridge pattern. This is accomplished with a thin layer of gold.

Answer 12

What is vacuum metal deposition (VMD)?

Question 13

This technique uses fluorescent dye to reveal fingerprints on nonporous surfaces.

Answer 13

What is staining?

Question 14

What is the ideal flowchart for fingerprint detection on nonporous surfaces?

Answer 14

Optical (no powder) > cyanoacrylate fuming/VMD > luminescent dye

Question 15

What compound is used to detect fingerprints on a porous surface like paper or wood?

Answer 15

Ninhydrin

Question 16

This purple compound is produced when the amino acids in a fingerprint interact with ninhydrin.

Answer 16

What is Ruhemann’s purple?

Question 17

Is ninhydrin photoluminescent or chemiluminescent? Why?

Answer 17

Photoluminescent because light is not produced from the reaction itself

Question 18

This improvement to ninhydrin fingerprinting using a metal salt solution such as { } produces a luminescence that enhances fingerprints.

Answer 18

Zinc Chloride

Question 19

This reagent used for developing latent prints on paper uses excitation at 470-550 nm to produce emission at 570-620 nm.

Answer 19

What is DFO?

Question 20

This water-insoluble reagent is great for prints on porous, wet surfaces and contains silver ions in a solution of Iron (II) and (III) to produce a redox reaction.

Answer 20

What is Physical Developer (PD)?

Question 21

What is the flowchart for fingerprint detection on porous surfaces?

Answer 21

Optical powder > DFO > ninhydrin/metal salt treatment > PD