Lab Deck (Midterm) Flashcards
In terms of quality assurance, why do we need calibration in forensic lab practice?
To ensure the quality of our results and the integrity of our data are not questionable
How many microliters are in a milliliter?
1000
The closeness of measurements to each other.
What is precision?
The closeness of a value to its true value.
What is accuracy?
This tells you how far the values in your data set deviate from the mean.
What is standard deviation?
This is a measure of the ratio of the standard deviation to the mean represented as a percentage.
What is the coefficient of variation?
Are color tests presumptive or confirmative?
Presumptive
What 3 factors affect the probability that a presumptive drug test on a dollar bill will be positive?
1) Age
2) Denomination of note
3) Location of circulation
What drug does the Scott reagent test?
Cocaine
What drug does the Marquis reagent test?
Meth
What color is a positive Scott test?
Blue
What color is a negative Scott test?
Pink
What color is a positive Marquis test?
Red/orange
What color is a negative Marquis test?
Black/brown
Why should you wear gloves and work under the fume hood with the Marquis reagent?
It contains very concentrated sulfuric acid
What was the positive control for the Scott reagent?
Diphenhydramine HCl
This physical property of matter relates an object’s mass to its volume.
What is density?
This rule states that an object immersed in a fluid displaces a fluid volume equal to its volume.
What is Archimede’s principle?
What is a comparative method of analyzing density?
Flotation
What does it mean for a particle to float in a liquid?
The liquid is more dense
What does it mean for a particle to sink in a liquid?
The liquid is less dense
What does it mean for a particle to remain suspended in a liquid?
The particle and liquid are equally dense
Why does light refraction occur?
There is a difference in density between two mediums that changes the velocity of light
This is the ratio of the speed of light in a vacuum to the phase velocity of light in a particle medium.
What is the refractive index?
What is a qualitative/comparative method for determining the range of a refractive index?
Becke line method
For the Becke line method, what does it mean when the halo moves from the liquid to the object being assessed (liquid>object)?
The object has a greater refractive index than the liquid
For the Becke line method, what does it mean when the halo moves from the object being assessed and into the liquid (object>liquid)?
The liquid has a greater refractive index than the object
What does it mean when the angle of refraction is close to the normal line?
Light is moving into a slower medium
What does it mean when the angle of refraction is away from the normal line?
Light is moving into a faster medium
What 2 factors affect density?
Temperature and pressure
