(Courtesy of Prof. Nihat Berker)
Consider doing the Frank-Hertz experiment as in the diagram below.
is the accelerating voltage, d is an infinitesimal retarding
voltage. The experimental vessel contains ``atomic'' systems which
can be represented by particles of mass m, each bound in an infinite
square well potential of width a. (The energy levels for such
square wells are derived in the class notes CN ``Bohr-Sommerfeld
Quantization...'') 
is the electron current and 
is the
emitted light intensity. Plot the behavior of these two quantities as
is scanned from 0 to 
.