In a video demonstration (not animation), cathode rays appear as a beam of green light moving from the cathode to anode inside the tube. The demonstrator brings a magnet near the tube and the green beam deflects. This I can understand. What I can not understand is that how the electron beam which are invisible are made to appear as a green beam and the beam also beautifully bends. What we have read is the fluorescent glow appears only when it strikes the glass. But how the path of the cathode rays in the gaseous part of the tube glows? 2.In the paddle wheel demo. when the cathode rays hit the wheel it rotates and moves in the forward direction, but how it moves in the reverse direction? 3.When a maltese cross is placed in the path of the cathode rays, a dark shadow in the shape of the cross appears on the fluorescent screen.When the cross is folded down, a fluorescent glow in the shape of the cross appears in the same place previously occupied by the shadow. I could understand the previous phenomenon but not the latter. If any body gives simple explanation for the above questions, it will be helpful to me.