can we create measuring device using our observed properties of light?
DESCRIPTION
Can we create measuring device using our observed properties of light?. What would we need to know to determine if our device was accurate?. How do we know our spring scales are accurate?. 1 kg. How do we know spring scales are accurate?. stretch (cm). offset or “blank”. mass (kg). - PowerPoint PPT PresentationTRANSCRIPT
Can we create measuring device using our observed properties of light?
What would we need to know to determine if our device was accurate?
How do we know our spring scales are accurate?
1 kg
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
offset or “blank”
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
1 kg
SI Units and time
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
2 kg
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
How do we know spring scales are accurate?
1 kg 4 kg2 kg
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
How do we know spring scales are accurate?
0 1 2 3 4 5 60.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
stre
tch
(cm
)
mass (kg)
Calibration curve
What mass causes a stretch of 5.5 cm?
=4.34 kgFinal calibration dataStretch = mass (1.13) + 0.60Mass = (stretch – 0.60) / 1.135.5 cm
What would we need to know to make an accurate calibration curve for our
device?
Tank of milk and water
light sensor
Let’s look at milk fat globules in water
+using serial dilutions
0.2 mm diameter FOV
Homogenized milk contains many small globules of fat
Each mL of 2% milk contains about 10 million globules
…this “population density” is about 1010 globules/L
Visible light is scattered nicely by these globules, about 5 m across on average
Why milk?
About 10 m diameter glob is a big one
ten billion
Which is the size of many exxtremophile microbes we’ll be looking for .
The intensity of light that is transmitted decreases when the
milk fat density. . .
(millions of globules per liter)
(photoresistorvoltage) What will the
graph look like?
…what would our measurements be?
Will the calibration curve be similar for a smaller device utilizing the
same properties of light?• Insert picture & explanation of handheld
spec here