Photoelectric Effect Apparatus
Model No. AP-8209
25
®
Table 9: Current and Voltage, Constant Frequency, Different Apertures
Experiment 3: Measuring Current-Voltage Characteristics of Spectral Lines -
Constant Aperture, Different Frequencies
The illustration shows typical data for current
versus voltage for a three spectral lines
(435.8 nm, 546.1 nm, 577.0 nm) with the 4
mm diameter aperture.
The next table shows typical data for current
versus voltage for a constant aperture and
three different frequencies.
Table 10: Current and Voltage, Different Frequencies, Constant Aperture
Questions: Experiment 1 - Planck’s Constant
1.
How does your calculated value of
h
compare to the accepted value?
The calculated value of
h
for the 4 mm diameter aperture is within 1.8% of the accepted value of
h
.
Student answers will vary.
2.
What do you think may account for the difference – if any – between your calculated
value of
h
and the accepted value?
λ
= 435.8 nm
2 mm dia.
V (V)
-1.1
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
2.2
4.4
5.9
7.2
8.3
9.4
10.4
11.2
11.9
12.6
13.3
λ
= 435.8 nm
4 mm dia.
V (V)
-1.1
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
6.8
14.7
19.9
24.5
28.2
32.1
35.2
38.2
41.2
43.5
46.4
λ
= 435.8 nm
8 mm dia.
V (V)
-1.1
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
27.2
59.7
79.9
97.7
111.6
123.8
133.7
144.5
154.4
162.9
170.4
λ
= 435.8 nm
4 mm dia.
V (V)
-1.1
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
6.8
14.7
19.9
24.5
28.2
32.1
35.2
38.2
41.2
43.5
46.4
λ
= 546.1 nm
4 mm dia.
V (V)
-0.5
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
1.3
3.1
4.5
5.3
6.1
6.6
7.2
7.8
8.2
8.7
9.2
λ
= 577.0 nm
4 mm dia.
V (V)
-0.3
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10
I (x 10
-11
A)
0.0
0.5
2.0
2.8
3.3
3.8
4.3
4.7
5.0
5.3
5.6
5.9