Spark image

Electron diffraction

The electron gun shoots a beam of electrons across the tube. The beam collides with a thin piece of graphite and the electrons diffract forming diffraction rings on the circular piece of fluorescent material at the far side of the tube. Moving the slider to the right increases the accelerating voltage and so reduces the electron wavelength which means smaller diffraction rings.

 
 
 
© Keith Gibbs/John Bourne 2011