The purpose of this experiment was to experimentally measure
the wavelength of the colors of light, hydrogen, and an unknown gas.
Procedure:
We used the setup below to find the distance of specific
color bands through a diffraction gradient.
The equation used to find the wavelength was:
L is the length, which is 1.90m. D is the distance of the
color band. d is the slit spacing of the
diffraction gradient, which is 1/500mm.
Data:
Light
D(cm)
|
λ(nm)
|
|
Shortest
|
40
|
412
|
Longest
|
77
|
751
|
Blue
|
49
|
499
|
Green
|
54
|
547
|
Yellow
|
58
|
584
|
Red
|
68
|
674
|
Using the shortest and longest wavelength, and the fact that
average humans can see between 390nm to 750nm, we found an equation to help
reduce the systematic error.
We plug in the calculated values of λ, and get a new
wavelength that is more accurate. I will call this λ’.
Hydrogen
The actual value for hydrogen was calculated by:
D(cm)
|
λ(nm)
|
λ'(nm)
|
actual
values of λ(nm)
|
% error
|
|
End of violet
|
42
|
432
|
411
|
410
|
0.002
|
Middle of
cyan
|
48
|
490
|
473
|
434
|
0.09
|
Red
|
67
|
665
|
658
|
656
|
0.003
|
Unknown Gas
D(cm)
|
λ(nm)
|
λ'(nm)
|
|
1st
violet
|
43
|
441
|
421
|
Last red
|
74
|
726
|
723
|
Cyan
|
47
|
480
|
462
|
Green
|
53
|
537
|
523
|
1st
yellow
|
59
|
593
|
582
|
Orange
|
61
|
611
|
602
|
Brightest
red
|
65
|
647
|
640
|
Analysis:
The unknown gas was determined to be Neon because of its
very distinctive pattern with many color bands.
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