PHGN 300 Homework #5
1. Plot the total number of known elements vs year starting from 1730 to 2010 in 10 year
intervals. Include the table of your data and the plot. Suggest getting data from
www.ptable.com No credit for copying a plot from the internet.
2. What is the series limit (that is, the smallest wavelength) for
a. The Lyman Series?
b. The Balmer Series?
c. The Brackett Series?
3. Calculate the 4 largest wavelengths for the Brackett and Pfund series for Hydrogen.
4. How much kinetic energy must an alpha particle have before its distance of closest approach
to a gold nucleus is equal to the nuclear radius (7.0 x 10-15 m)?
5. Protons of energy 5.0 MeV are incident on a silver foil of thickness 4.0x10-6 m. What fraction
of the incident protons is scattered at angles: (a) greater than 90 degrees, (b) greater than 10
degrees (c) between 5 degrees and 10 degrees (d) less than 5 degrees ?
Extra credit:
Estimate the fraction of the solar system that is empty space. Quantitatively how does this
fraction compare to that for a typical atom? To receive credit, you need to state clearly what
numbers you are using as an input, the equations you are using, and the results. To receive
credit your work must be well organized and legible to the grader.