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[Pat Murphy's Maze of Twisty Little Passages]

Exam Passages

Recently, while rummaging through some old files in my office, I came across the questions to my last exam in my final year of college as an undergraduate. This was the 4th year Experimental Physics exam, "Fifth Paper" (in Ireland, exams such as that are called papers). I had annotated my name and the date on the top: 11th September, 1978. These are just the questions; I don't have the actual answers I wrote anymore -- probably just as well!

This was the last time all of us in the Physics "Class of '78" were together in one place (other than at graduation). It may seem a little corny, but I wrote on the back of the paper this little comment:

...Thus ends a way of life.
--just as we were getting used to it. Although we may have cursed it time and time again over the last 4 years, there is left in most of us a pang of regret on its passing.

        P.M. 25/9/78

The paper was comprised of five different sections, representing different areas of physics covered in the coursework. Each section had three questions to be answered, and we had to answer any four questions total. I elected to answer all the questions in Section B (Astrophysics; go figure!) and one from section C (High Energy Physics). With apologies to professors Porter, O'Mongáin, Montwill and Breslin, here are the questions I attempted:

    4.    Write notes on black body emission, thermal emission from ionized hydrogen and synchroton radiation as sources of radio frequency radiation. Show how knowledge of the radiation mechanism can lead to information on particle energies in radio sources.

    5.    Describe the properties of the charged primary cosmic radiation.
    Cosmic ray protons are thought to be coming from a supernova 2 kpc away. Above what energy will they appear to be coming from within 10° of the supernova if the mean galactic magnetic field perpendicular to the line of sight is 3 µ gauss? (1 pc = 3 × 1018 cm).

    6.    Discuss the present status of gamma-ray astronomy.

    8.    Give an account of the production and decay of hypernuclei.
    A hypernucleus decays at rest into a proton, α particle and negative π meson of kinetic energies 1.9 MeV, 0.6 MeV and 32.2 MeV respectively. What is the identity of this hypernucleus? Calculate the binding energy of the Λ-hyperon.

        Mass of proton = 938 MeV/c2
        Mass of π meson = 138.6 MeV/c2
        Mass of Λ hyperon = 1115.6 MeV/c2

Given where I ended up working, it's a little eerie to re-read that first question...

[Powered by Apache!] Patrick P. Murphy
National Radio Astronomy Observatory
Charlottesville, Virginia, USA