Diagram of <a href="https://en.wikipedia.org/wiki/Crookes_tube" class="extiw" title="wikipedia:Crookes tube">Crookes tube</a>, an experimental discharge tube invented by <a href="https://en.wikipedia.org/wiki/William_Crookes" class="extiw" title="wikipedia:William Crookes">William Crookes</a> around 1875.  The power supply applies a voltage of several thousand volts between the two electrodes.  Electrons (cathode rays) released from the cathode plate are accelerated down the tube to the left toward the anode, and strike the end wall, which fluoresces.  The Maltese cross shaped anode blocks the electrons, casting a shadow on the glowing end wall, demonstrating that the cathode rays travel in straight lines.  The electrons eventually make their way to the anode, travel up the anode wire, through the power supply, and back to the cathode.  Drawing made with Inkscape.
Chris Burks <a href="//commons.wikimedia.org/w/index.php?title=User:Chetvorno&amp;action=edit&amp;redlink=1" class="new" title="User:Chetvorno (page does not exist)">Chetvorno</a>
5/3/08
<span class="int-own-work" lang="en">Own work</span>