Electron Diffraction

Purpose

Demonstrate the wave properties of electrons.◙

Equipment

Pre-assembled electron diffraction apparatus.◙

Images

p2-13

Description

Electrons are emitted by the cathode at the back end of the tube, are accelerated by a high voltage and strike a target of powdered graphite crystals, producing a characteristic circular diffraction pattern. The pattern can be seen when the diffracted electrons strike a phosphorescent coating at the front end of the tube. As the accelerating voltage is increased, decreasing the wavelength of the electrons, the circles become larger. Quantitatively, the radius of the circle can be measured to be inversely proportional to the wavelength, which is approximately inversely proportional to the squar

References

C. J. Calbick, The Discovery of Electron Diffraction by Davisson and Germer, TPT 1, 63-69, 91, (1963). ◙Richard Schlegel, Wave and Inertial Properites of Matter, AJP 22, 77-82, (1954). ◙Catalog Sheet, BP 117 Diffraction Tube System, Kickok Science. ◙Instructions Manual, Electron Diffraction Tube TEL 555, Teltron Limited.