Reference no: EM13539896

A focused magnetic field of variable strength is used to "steer" electrons in a television tube (CRT). The electrons emerge in a stream from a "gun" that has accelerated them across a potential difference. A magnetic field can deflect the beam of electrons in various directions. They then travel to the tube's front inside surface on the TV screen, where they strike red, green, or blue phosphors and cause them to glow, creating part of one pixel in a picture display (actual color tubes use three guns, one for each color). Use the orientation of the components as shown in the illustration to answer these questions. (a) In what direction should the magnetic field point to deflect the electron beam upward, toward the top of the tube? (b) A TV tube plays the electron beam over its picture screen in a raster pattern, moving it from one side of the screen to the other at the very top of the tube, then all the way across the screen at a lower point, and again and again at still lower points, until the whole screen is painted with sideways sweeps. A second magnetic field of varying strength, which is not shown in the illustration, deflects the beam from side to side at each one of its vertical positions. Suppose a beam is heading straight toward the left in the illustration (it is not deflected vertically). In what direction would the second field have to point to deflect the beam toward you?