User's Manual

SE-9639 Franck-Hertz Experiment
20
012-14264A
Table 2: Peak and Valley Voltages
Analysis
Obtain the value of argon atom’s first excitation potential (V
0
):
V
0
(peak) = (V
6
- V
1
)/5 = 11.3 V;
V
0
(valley) = (V
6
- V
1
)/5 = 12.0 V;
Therefore: V
0
= 11.65 V;
Calculate the value of Planck’s Constant, h
where e = 1.602 x 10
-19
C,  = 108.1 nm, and c = 3 x 10
8
m/s. Based on the data, Planck’s Constant, h = 6.725 x 10
-34
J•s
Calculate the percent difference between the experimental value and the accepted value (h
0
=6.626 x 10
-34
J•s)
h = | (h - h
0
) / h
0
| x 100% = 1.5%.
Questions
1. Should you use the positions of the peaks or of the valleys to determine the excitation energy? Or both? Explain.
V
1
V
2
V
3
V
4
V
5
V
6
Peak
positions
V
G2K
(V) 22.53243556679
I
A
(x 10
-10
A) 153 448 825 1216 1522 1760
Valley
positions
V
G2K
(V) 13 26 38 49 61 73
I
A
(x 10
-10
A) 1 118 145 113 118 227
he
V
0
c
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=