Pure silver has a work function of
0 = 4.7eV
. A crude calculation of the type used in the
text, using the atomic weight and density of silver, gives a spacing between atoms in a silver
crystal of about d = 12nm. Note that d-cubed was taken to be the mass-per-atom divided by
the density of the silver. It has been found that light of intensity
10 2 I W m 1 10−
=
can still
cause photoemission from silver. If the electromagnetic wave interpretation were correct,
how long would it take before the first photoelectrons were emitted?