Question 8-29D2

Cathode Ray Tubes (CRTs) generate an image by accelerating a beam of electrons towards a phosphorescent screen. To create a bright, visible image, the electrons must strike the screen with significant kinetic energy. This energy is imparted by a very strong electric field, created by a high positive voltage applied to the accelerating anode. Voltages in the kilovolt (kV) range are necessary to provide enough acceleration for the electron beam to penetrate the phosphor and produce luminescence. Options A and C (millivolts) are far too low and would not accelerate electrons sufficiently to create any visible light. Option D (hundreds of volts) is also inadequate for the main accelerating anode of a display CRT, which requires much higher voltages to achieve a practical display. Therefore, 10-50 kV is the typical range for CRT anode circuits.