Lab 5
Frank Hertz Experiment
Bill Chun Wai Hung
Nimish Kumar
Friday Section
13 May 2004
Data:
Valley |
Voltage (eV) |
Voltage Difference (eV) |
1 |
8.597 |
N/A |
2 |
13.092 |
4.495 |
3 |
17.823 |
4.731 |
4 |
22.923 |
5.100 |
Calculation:
The average voltage difference is eV
The percentage difference is
Conclusion by Bill Chun Wai Hung:
1. Principles and Results
The voltage value of
the valleys of the graph is measured to by 4.495eV, 4.731eV, and 5.100eV. The
average voltage difference is 4.775eV. The percentage difference is 2.54%.
By using the Franck-Hertz Apparatus, the
electrons are shot from one end and if the electrons have enough energy, then
they will pass the repulsion force generated by the potential difference from
the battery. By measuring the amount of electron passing through the potential
barrier, the energy level from the emission of light from mercury can be
measured.
From the computer-generated graph, there
are peaks and valleys representing the current passing through the circuit. The
different amount of current passing through the circuit is depended on the
amount of electron that successfully reached the target plate. In other words,
by calculating the difference of the valleys, the difference of energy level of
the ”°higher energy electrons”± can be determined.
The target value of
the mercury energy level is 4.9eV, and the experimental mercury energy level is
.4.775eV.
2. Error Analysis
The electronmeter
are so sensitive, so the electrical equipments surrounding the electronmeter
can actually interfere with the measurement of the result. This is because when
a wire is moved, the current in the wire generates a magnetic field, and the
magnetic field interferes with the reading of the electronmeter. However, in
the case of this experiment, the equipments and wires are not moved, so the
reading of the electronmeter is not affected too much.
There was an
intrinsic error during the time the experiment was performed. Dr. Jordan and
his students could not find out the problem exactly, but the reading of the
voltage continued to go up for the earlier readings. The reading obtained by
this report is a more accurate reading from the laboratory.