Color and Spectra

Objective

 To visualize the quantization of energy levels by viewing emitted photon wavelengths and using spectroscopy to identify an unknown gas.

Equipment

Apparatus

• 2 meter sticks (one 2m and the other 1m)
• Stands
• A Diffraction Grading
• Incandescent lamp
• Hydrogen Tube
• florescent tube
• Misc Tube

Procedure

Place the meter sticks at a 90 degree angle as close as possible to the to the light source, taking high voltage precautions (i.e. only handle lamp with one arm)
      The lights in the room were then shut off. The diffraction grating was then placed at a known distance from the lamp. One future engineer observes through the grating while another moves his finger over the other meter stick and notes the distances at which the former sees the spectra. 
     We observed a violet to red spectrum with violet being closest to the bulb. The wavelengths recorded were:

violet edge	36.7	±	0.5	m
blue	45.5	±	0.5	m
green	53.7	±	0.5	m
red	70.3	±	0.5	m
red edge	83.5	±	0.5	m

we derove the following:

Values for our experiment:
     L=1.96  0.003m
     d=0.0020 mm

Using the true values for the colors viewed in the experiment along with the measured values a correcting linear function was obtained as shown below

Having this equation allowed us to correct any errors in future wavelengths.

 

 For the next part, to test our calculation and the theoretical values of hydrogen spectrum, we examined the spectrum lines for hydrogen.
the procedure was repeated to view the spectra of the Hydrogen lamp yielding the values noted below. as well as the percent error in our measurements.

Diffraction Grating

Finally we received a tube with an unknown gas from our professor and repeated the experiment once again obtaining these values.

Using the internet to look up spectrum lines and values, we discovered that our unknown was Xenon.