Plank's constant Experiment Notes.
To do list:
 Identify security issues.
 Read the lab manual. (Done)
 Read article in Wikipedia
 Read past experiments related to this one.
 Identify the kinds of analysis that are going to be used in this lab.
 Check the two battery voltages.
Equipment
 PASCO AP9368 h/e Device
 2 9V OPAmp Batteries
 PASCO OS9282 Scientific Hg Light Source
 Tektronix TDS 1002 Digital Oscilloscope
 Wavetek 85XT RMS DVM
Some formulas for later
Equations
In effect quantitatively using Einstein's method, the following equivalent equations are used:
Energy of photon = Energy needed to remove an electron + Kinetic energy of the emitted electron
Algebraically:
http://upload.wikimedia.org/math/b/d/4/bd44368c6a5fe759a79feb0cac2e05a4.png
where
 http://upload.wikimedia.org/math/b/0/f/b0f540b2cf63fcb37995455670be5cbd.png is Planck's constant,
 f is the frequency of the incident photon,
 \phi = h f_0 \ is the work function (sometimes denoted W instead), the minimum energy required to remove a delocalised electron from the surface of any given metal, E_{k_{max}} = \frac{1}{2} m v_m^2is the maximum kinetic energy of ejected electrons,
 f0 is the threshold frequency for the photoelectric effect to occur,
 m is the rest mass of the ejected electron, and
 vm is the speed of the ejected electron.
Since an emitted electron cannot have negative kinetic energy, the equation implies that if the photon's energy (hf) is less than the work function (φ), no electron will be emitted.
Data
Green Filter/Green Light
Relative Tran.

Voltage

Time 1

Time 2

Time 3

Time 4

Time 5

Relative Tran. 100% 
.883 +/ .001 V 
14.97s 
14.06s 
16.41s

Relative Tran. 80% 
.884 +/ .001 V 
16.9s 
13.4s 
15.78s 
12.75s 
13.16s

Relative Tran. 60% 
.883 +/ .001 V 
25.8s 
19.75s 
18.31s 
17.72s

Relative Tran. 40% 
.882 +/ .001 V 
28.44s 
23.66s 
16.56s

Relative Tran. 20% 
.882 +/ .001 V 
84.44s 
29.25s 
50.00s

Yellow Filter/Yellow Light
Relative Tran.

Voltage

Time 1

Time 2

Time 3

Relative Tran. 100% 
.740 /+ .001 V 
15.40s 
18.09s 
17.22s

Relative Tran. 80% 
.740 /+ .001 V 
17.88s 
15.53s 
16.69s

Relative Tran. 60% 
.738 /+ .001 V 
22.85s 
18.41s 
22.50s

Relative Tran. 40% 
.735 +/ .001 V 
28.56s 
24.19s 
27.00s

Relative Tran. 20% 
.735 +/ .001 V 
45.40s 
46.50s 
49.35s

Ultraviolet Light
Relative Tran.

Voltage

Time 1

Time 2

Time 3

Time 4

Relative Tran. 100% 
1.6585 /+ .0005 V 
18.91s 
17.18s 
17.11s

Relative Tran. 80% 
1.6735 /+ .0005 V 
27.30s 
26.25s 
30.69s

Relative Tran. 60% 
1.6545 /+ .0005 V 
36.56s 
30.35s 
31.09s

Relative Tran. 40% 
1.6795 +/ .0005 V 
34.35s 
37.22s 
35.91s 
37.90s

Relative Tran. 20% 
1.6715 +/ .0005 V 
74s 
72s 
76.09s

Manuel and I think it is a good idea to stay around 20 minutes after next class to take a few more measurements to improve the analysis. Since we already have the data analysis done, it will be quick and easy to introduce the new numbers and get an improved result.
Determination of h
Measurements of 1st order
Color

Measurement 1 (V)

Measurement 2 (V)

Measurement 3 (V)

Measurement 4 (V)

Measurement 5 (V)

Ultraviolet 
2.0655 +/ .0005 
1.8595 +/ .0005 
1.6435 +/ .0005 
1.6515 +/ .0005 
2.1 +/ .1

Violet 
1.6575 +/ .0005 
1.5745 +/ .0005 
1.4025 +/ .0005 
1.4065 +/ .0005 
1.708 +/ .001

Blue 
1.4345 +/ .0005 
1.3755 +/ .0005 
1.2375 +/ .0005 
1.2325 +/ .0005 
1.491 +/ .001

Green w/ filter 
.8035 +/ .0005 
.7875 +/ .0005 
.7385 +/ .0005 
.7415 +/ .0005 
.851 +/ .001

Yellow w/ filter 
.6775 +/ .0005 
.6785 +/ .0005 
.6315 +/ .0005 
.6305 +/ .0005 
.714 +/ .001

After taking several measurments something strange happended with the voltmeter. The measurments started to drop from their previous values. We could not explain why this was happening, but we decided to carry on with the measurments and perform the data analysis later to get a better perspective on the results.
Measurements of 2st order
Color

Measurement 1 (V)

Measurement 2 (V)

Measurement 3 (V)

Measurement 4 (V)

Ultraviolet 
1.665 +/ .005 
1.6435 +/ .0005 
1.6395 +/ .0005 
1.6385 +/ .0005

Violet 
1.5395 +/ .0005 
1.4845 +/ .0005 
1.4505 +/ .0005 
1.4315 +/ .0005

Blue 
1.4715 +/ .0005 
1.4175 +/ .0005 
1.3745 +/ .0005 
1.3575 +/ .0005

Green w/ filter 
1.1115 +/ .0005 
1.1145 +/ .0005 
1.1095 +/ .0005 
1.1075 +/ .0005

Yellow w/ filter 
.6755 +/ .0005 
.6835 +/ .0005 
.6855 +/ .0005 
.6885 +/ .0005

Manuel 4:29 pm, 19 Nov 2008 (EDT): So here is the link to my raw data
Manuel and I think it is a good idea to stay around 20 minutes after next class to take a few more measurements to improve the analysis. Since we already have the data analysis done, it will be quick and easy to introduce the new numbers and get an improved result.
Results and Analysis
Even though we are going to take some more data, I think it is convenient to do some analysis now so when the new data comes in, we can just plug in.
Experiment #1 (The Photon Theory of Light)
Analysis for part #1
File:Plank's Contant Part 11.xls
Green Line with Green Filter
 Average maxV:0.8821 V
 STD:0.00083666
 SEM:0.000374166
Charge Time vs Relative Intensity
Voltage Vs Relative Intensity
Yellow Line with Yellow Filter
 Average maxV:0.8821 V
 STD:0.00083666
 SEM:0.000374166
Charge Time vs Relative Intensity
Voltage Vs Relative Intensity
Ultraviolet
 Average maxV:0.8821 V
 STD:0.00083666
 SEM:0.000374166
Charge Time vs Relative Intensity
Voltage Vs Relative Intensity
The purpose of this part of the experiments was to prove 2 things.
Experiment #2 Determination of h.
Results. File:Plank's Constant Part 2.xls
Actual Plank constant:(4.13)E15 eV*s
Measured h:(3.72±0.16)E15 eV*s
Percent Error:9.92%
Actual work constant:1.36(8) eV
Measured W0=(1.66±0.01)V
Percent Error:22.05%
Aknowledgments
I used Ariannas Excel analysis to guide me through my analysis.
