GOALS

Physics

• Measure the energy difference between the ground state and the first excited state in mercury atoms.

Techniques

• Compare the oscilloscope and the x-y recorder as instruments for measuring the collector current as a function of electron accelerating voltage.
• Learn how to optimize the experimental conditions for obtaining useful data.

Error

• Calculate whether your mean value for the energy difference is in reasonable agreement with one of the principal lines in the mercury spectrum.

Question (work out in lab book before class)

1. What are the wavelengths of the three longest wavelength lines in the Balmer series of spectral lines for hydrogen (Fig. 1).

References

• Wehr, Richards and Adair; 4.5--4.9
• Halliday and Resnick; 42--8.