13 Figure 2A. Cold-cathode tube operation. 2-30. If the source voltage in figure 2A is increased to 150 volts and the ammeter reads 20 milliamperes, what is the resistance (rkp) of the tube?   1.    2.65 k W   2.    5.25 k W   3.    6.25 k W   4.    8.15 k W 2-31. The electron gun of the CRT serves which of the following functions?   1.    Deflects electrons into the plate   2.    Concentrates electrons into a beam   3.    Emits electrons   4.    Both 2 and 3 above 2-32. Which of the following is a description of the grid in a CRT?   1.     A metal cap with a hole in the center   2.     A metal cap at ground potential   3.     A metal cap with a positive potential   4.     A metal cap with a wire screen in the center 2-33. What element of a television CRT is adjusted by the brightness control?   1.    Cathode   2.    Aquadag   3.    Control grid   4.    Focusing anode 2-34. Which of the following elements of the CRT helps prevent the beam of electrons from diverging?   1.    Cathode   2.    Aquadag   3.    Focusing anode   4.    Decelerating anode 2-35. Which of the following elements of a CRT has the highest positive potential?   1.    The focusing anode   2.    The electronic lens   3.    The accelerating anode   4.    The decelerating anode 2-36. What is the name of the florescent material that coats the inside face of a CRT?   1.    Posporus   2.    Phosphor   3.    Flourine   4.    Flourese 2-37. What is the purpose of the aquadag coating in the CRT?   1.     It is used as a plate   2.     It is used to focus the beam   3.     It eliminates the space charge   4.     It eliminates the effects of secondary emission