Lab Deck (Midterm)

Question 1

In terms of quality assurance, why do we need calibration in forensic lab practice?

Answer 1

To ensure the quality of our results and the integrity of our data are not questionable

Question 2

How many microliters are in a milliliter?

Answer 2

1000

Question 3

The closeness of measurements to each other.

Answer 3

What is precision?

Question 4

The closeness of a value to its true value.

Answer 4

What is accuracy?

Question 5

This tells you how far the values in your data set deviate from the mean.

Answer 5

What is standard deviation?

Question 6

This is a measure of the ratio of the standard deviation to the mean represented as a percentage.

Answer 6

What is the coefficient of variation?

Question 7

Are color tests presumptive or confirmative?

Answer 7

Presumptive

Question 8

What 3 factors affect the probability that a presumptive drug test on a dollar bill will be positive?

Answer 8

1) Age
2) Denomination of note
3) Location of circulation

Question 9

What drug does the Scott reagent test?

Answer 9

Cocaine

Question 10

What drug does the Marquis reagent test?

Answer 10

Meth

Question 11

What color is a positive Scott test?

Answer 11

Blue

Question 12

What color is a negative Scott test?

Answer 12

Pink

Question 13

What color is a positive Marquis test?

Answer 13

Red/orange

Question 14

What color is a negative Marquis test?

Answer 14

Black/brown

Question 15

Why should you wear gloves and work under the fume hood with the Marquis reagent?

Answer 15

It contains very concentrated sulfuric acid

Question 16

What was the positive control for the Scott reagent?

Answer 16

Diphenhydramine HCl

Question 17

This physical property of matter relates an object’s mass to its volume.

Answer 17

What is density?

Question 18

This rule states that an object immersed in a fluid displaces a fluid volume equal to its volume.

Answer 18

What is Archimede’s principle?

Question 19

What is a comparative method of analyzing density?

Answer 19

Flotation

Question 20

What does it mean for a particle to float in a liquid?

Answer 20

The liquid is more dense

Question 21

What does it mean for a particle to sink in a liquid?

Answer 21

The liquid is less dense

Question 22

What does it mean for a particle to remain suspended in a liquid?

Answer 22

The particle and liquid are equally dense

Question 23

Why does light refraction occur?

Answer 23

There is a difference in density between two mediums that changes the velocity of light

Question 24

This is the ratio of the speed of light in a vacuum to the phase velocity of light in a particle medium.

Answer 24

What is the refractive index?

Question 25

What is a qualitative/comparative method for determining the range of a refractive index?

Answer 25

Becke line method

Question 26

For the Becke line method, what does it mean when the halo moves from the liquid to the object being assessed (liquid>object)?

Answer 26

The object has a greater refractive index than the liquid

Question 27

For the Becke line method, what does it mean when the halo moves from the object being assessed and into the liquid (object>liquid)?

Answer 27

The liquid has a greater refractive index than the object

Question 28

What does it mean when the angle of refraction is close to the normal line?

Answer 28

Light is moving into a slower medium

Question 29

What does it mean when the angle of refraction is away from the normal line?

Answer 29

Light is moving into a faster medium

Question 30

What 2 factors affect density?

Answer 30

Temperature and pressure