• A white light next to the electron gun casts a faint shadow of a maltese cross onto the front screen of an evacuated tube.
  • When the high voltage is increased to 2000 V, electrons strike the luminescent screen creating another shadow surrounded by green light.  Both shadows overlap exactly, showing that electrons propagate linearly.

        (refer to tube manual for wiring diagram)

  • Close up of luminescent screen.
  • Best results obtained with room lights dimmed.