The purpose of this experiment is to calculate the electron wave length and verify the hypothesis of Louis De Broglie, proposed in 1924 by the Fench physicist Louis De Broglie, who received the Nobel Prize in Physics in 1929. He considered that both electrons and other particles exhibit the wave properties, and the wave length was determined by the momentum of the particle. This experiment uses high voltage source to accelerate electrons by 2500~5000 volts to have the electrons injected to a graphite crystal and to observe the diffraction pattern on the screen.

Electron Diffraction Tube
The electrons are emitted from the cathode and accelerated to the graphite target by the high voltage supply (2500 ~ 5000 volts). After passing through the graphite target they have sufficient energy to light up the phosphor screen when they hit it.

Multimeter
Using the digital multimeter allows you to monitor the current to prevent the graphite from spalling.

High DC Voltage Source
2500~5000 volt high power voltage to accelerate electrons to high velocities.

Power Supply
With a 6.3V input voltage to the electron source gun filament.
Intensity of the electron beam can be controlled by altering the bias voltage (Usually 0~50 volt).

Video

Electron Diffraction

Department of Physics (Digital Archive Project of NTU General Physics Laboratory)
National Taiwan University