User's Manual

Franck-Hertz Experiment Questions
13
012-14264A
2. Find the peak (or valley) positions which match the accelerating voltages labeled “V1, V2, V3, V4, V5, and V6”.
3. Obtain the value of argon atom’s first excitation potential (V
0
).
4. 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.
5. 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% =
Questions
1. Should you use the positions of the peaks or of the valleys to determine the excitation energy? Or both? Explain.
2. Why are the peaks and valleys smeared out rather than sharp?
3. How precisely can you determine the peak/valley position? Explain and justify your estimates.
4. How would molecular contaminants in the tube affect your results?
V
0
V
2
V
1
–V
3
V
2
–V
4
V
3
–V
5
V
4
–V
6
V
5
–++++
5
----------------------------------------------------------------------------------------------------------------------------------------------------
=
he
V
0
c
------


=