
Solution for Graphing Spectra Student Worksheet,
Part II
The graphical representation should include all visible lines shown
in the color specrum. The continuum should rise gradually from 4000
angstroms, and remain fairly constant through blue, and decrease
slightly in green portion
of the spectrum. It should increase again, reach a maximum near
yellow, and then decline again in the red.
Below are the solutions for the identifying the lines in the spectra
of hydrogen and helium.
Hydrogen
We can identify three bright lines for hydrogen in the top spectrum.
Measuring from the scale, the wavelengths are 435 nm (purple), 486 nm
(blue) and 657 nm (red). Recall (e.g. from the
Calculation Investigation) that
the the frequency is given by
n = c / l,
and the energy is given by
E = hn
(where h = 6.626 x
10^{34}Js, and c = 3 x 10^{8} m/s). In the table
below we summarize the frequency and energy results for these lines.
(We include the color to aid in identifying the line in the spectrum.)
Wavelength (nm) 
Color 
Frequency (Hz) 
Energy (J) 
435 
purple 
6.90 x 10^{14} 
4.57 x 10^{19} 
486 
blue 
6.17 x 10^{14} 
4.09 x 10^{19} 
657 
red 
4.57 x 10^{14} 
3.03 x 10^{19} 
Helium
We can identify a number of lines in the spectrum of Helium.
The bright lines are listed in the table below, along with their
frequencies and energies. Students may identify any two of these.
Wavelength (nm) 
Color 
Frequency (Hz) 
Energy (J) 
447 
purple 
6.71 x 10^{14} 
4.45 x 10^{19} 
469 
blue 
6.40 x 10^{14} 
4.24 x 10^{19} 
472 
blue 
6.36 x 10^{14} 
4.21 x 10^{19} 
493 
bluegreen 
6.09 x 10^{14} 
4.03 x 10^{19} 
501 
bluegreen 
5.99 x 10^{14} 
3.97 x 10^{19} 
505 
bluegreen 
5.94 x 10^{14} 
3.94 x 10^{19} 
587 
yellow 
5.11 x 10^{14} 
3.39 x 10^{19} 
669 
red 
4.48 x 10^{14} 
2.97 x 10^{19} 
