Physics 1D Lab
Plank’s Constant
&
Photoelectric Effect
03/10/2014
Group Report
Lab Group:
PURPOSE:
In this lab, Plank’s constant is obtained by isolating different color
wavelengths, recording the values, and plotting voltage vs. frequency to obtain a
slope equal to e / h. H is then calculated with e / slope.
EQUIPMENT:
 Hg Light source (#54351)
 H/e apparatus (#001126)
 Voltmeter (#000156)
PROCEDURE:
White light is emitted from the light source. Using various filters designed to allow
specific wavelengths through, we can gather data related to the preselected colors.
The data is recorded and plotted to find a frequency vs. voltage slope where h = e /
slope.
DATA & ANALYSIS:
Color
Red
Yellow
Green
Blue
Vs(Stopping
Voltage)
0.341
0.686
0.726
1.28
Frequency
4.44E+00
5.19E+00
5.49E+00
6.88E+00
frequency
8.00E+00
y = 2.6184x + 3.5146
7.00E+00
6.00E+00
5.00E+00
4.00E+00
frequency
3.00E+00
Linear (frequency)
2.00E+00
1.00E+00
0.00E+00
0
0.5
1
1.5
𝑠𝑙𝑜𝑝𝑒 =
𝑒
ℎ
h
6.737E-34
6.3533E-34
6.755E-34
6.11154E-34
6.942E-34
6.056E-34
→𝒉=
𝑒
𝑠𝑙𝑜𝑝𝑒
5.97933E-70
1.93692E-70
6.89203E-70
1.4511E-69
2.02074E-69
1.90509E-69
6.85776E-69
=
1.60×10−19
2.618×1014
= 6.11 × 10−34
h-average
6.49247E-34
standard deviation
3.7034475E-35
Standard deviation of
the mean
1.5119261E-35
DISCUSSION:
The causes of error in this lab was due to the light source not being a laser. This
would cause each frequency to be at a possible different intensity. Also we were
not in a completely dark room so ambient light sources could have affected the
results.
CONCLUSION:
In this lab we calculated an h value of 6.11 × 10−34 . An h-average of 6.49 ×
10−34 was calculated for the class.
SUPPORTING DOCUMENTS: