| Modern
Physics > Quantum Effects > Photoelectric Effect |
DCS#
7A10.10 |
DISCHARGE OF ZINC
APPARATUS
| short-wave
uv lamp |
202-19-B |
| zinc plate |
202-19-E2 |
| electroscope |
202-19-C |
| rubber rod |
202-19-D6 |
| rabbit fur |
202-19-D4 |
| piece of glass |
101-06-E6 |
| gooseneck camera |
202-09-D |
DESCRIPTION
Rub the rod with the rabbit fur to
charge it negatively. Charge the zinc plate with the rubber
rod. The electroscope can be seen to discharge when
the zinc is illuminated with uv light from the Geology mineral lamp or
a mercury spectrum tube. The electroscope
does not discharge when a glass plate is inserted to block the uv.
NOTES
Rub rubber rod with rabbit fur or glass
rod with silk to obtain negative charge on rod.
Zinc must be sanded and free from
oxide
coating.
The work function of zinc is 3.63 eV,
corresponding to a threshold wavelength of 342 nm.
REFERENCES
B. Tolar,
"Experiments with a
photoelectric
electroscope," The Physics Teacher, vol.14, 502-503 (1976).
Freier and Anderson, Ok-3;
Meiners, 38-2.1;
Sutton, A-89.