If anyone is an expert on Velocity Modulation of Electrons within Electric Field, please try to help me. The dilemma is, I'm reading through waveguide theory on TPUB and hit a page that deals with VELOCITY MODULATION. http://www.tpub.com/content/neets/14183/css/14183_85.htm It clearly states at the bottom that as an electron moves in an electric field (accelerates against electric flux lines), it is gaining KINETIC ENERGY at the expense of ENERGY FROM THE ELECTRIC FIELD. Is this correct? And if so can someone tell me what that really means. From what I see, the electron would be gaining Kinetic Energy at the expense of it's own energy of position (POTENTIAL ENERGY it has by being in the position it was in). So how does the electron GIVE UP energy to the electric field?