CHEM1006 Lecture Notes - Lecture 9: Crookes Tube, Fluorescence, Johann Wilhelm Hittorf
Document Summary
Crookes found that as he pumped more air out of the tubes, the faraday dark space spread down the tube from the cathode toward the anode, until the tube was totally dark. At the anode end of the tube, the glass of the tube itself began to glow. What was happening was that as more air was pumped from the tubes, the electrons could travel farther, on average, before they struck a gas atom. By the time the tube was dark, most of the electrons could travel in straight lines from the cathode to the anode end of the tube without a collision. With no obstructions, these low mass particles were accelerated to high velocities by the voltage between the electrodes. When they reached the anode end of the tube, they were traveling so fast that, although they were attracted to it, they often flew past the anode and struck the back wall of the tube.
