PhysicsLAB Lab
Hydrogen Spectrum
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Equipment:

1 hydrogen spectrum tube
1 transformer
2 1-meter sticks
1 2-meter stick
1 ring stand
1 test-tube clamp
1 c-clamp
1 diffraction grating
2 white index cards



grating statistics: 13400 lines per inch = 1.90 x 10-6 meters/slit
 
What was the distance (in meters) from the grating to the 2-meter meterstick which was placed in front of your spectrum tube? 

Fill in the following chart after you INDIVIDUAL data collection and analysis have been signed off by Mrs. Colwell.

spectral line average x average theta average
wavelength 		photon
energy
red
cyan
violet
Refer to the following information for the next three questions.

Bohr derived that the ground state energy of a room-temperature hydrogen atom was - 2.18 x 10-18 J . He also determined that the lines in the Balmer series were produced by transitions of excited electrons from orbitals n = 3, 4, and 5 down to n = 2. If the energy of the first excited state (n = 2) is - 5.45 x 10-19 J complete the remainder of this energy level diagram using the energies you calculated in your lab. Show your work to obtain each value on your data papers.

energy level n = 3 _____________________ J 

energy level n = 4 _____________________ J 

energy level n = 5 _____________________ J 

Refer to the following information for the next five questions.

Complete the following conclusions.
Conceptually, why are all of the energy levels above negative?
 

In your data, which color has the greatest value of x (called its linear deviation)?
 
What property of this color (frequency or wavelength) explains why it has the greatest linear deviation?
 
In your data, which color represents a photon having the greatest energy?
 
What property of this color (frequency or wavelength) explains why it's photon has the greatest energy?
 
Refer to the following information for the next four questions.

Calculate your percent errors for each energy level: n = 3, 4, 5
n = 3 

n = 4 

n = 5 

Do you think that the percent errors in your energy level diagram would be smaller or larger if you had used these second order lines? Explain your decision. 




 
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