A full screen image is formed when the electron beam is deflected in the vertical and horizontal directions either by magnetic fields or the electrostatic effect of electrodes within the tube. The magnetic fields and the electrostatic effect of electrodes within the tube are produced by coils found in the neck of the tube.Some cathode-ray tubes use multiple beams of electrons, displaying more than one color. These are made for television, oscilloscopes, computer terminals, automated teller machines and radar displays.The voltage of a television picture tube has increased gradually. In the 1940s only 3000-6000 volts were needed for the final anode. Today, 25,000 volts are typical as television has advanced from small black and white sets to larger color screens.