AP 3302 Pt. 3
Section 2
CHAPTER 12
Timebase Principles
Let us suppose that we are using single-ended deflection in which X1 is permanently connected to earth. When X2 is also at earth potential there is no electric field between the plates and the spot is at the centre of the screen. To move the spot to its starting position at point P in Fig. 7 we make X2 negative with respect to earth. The voltage between the plates then produces an electric field which deflects the beam to the left-hand side of the screen at point P. Similarly, if X2 is positive with respect to earth the beam is deflected to the right-hand side of the screen towards point Q.
