FCC Exam Question: 8-30D4

How many deflection coils are driven by the sweep amplifier?

A. 4
B. 3
C. 2
D. 1
Correct Answer: C

Explanation: In a Cathode Ray Tube (CRT), an electron beam is used to draw waveforms or images on a screen. To move this beam, deflection systems are employed. The "sweep" refers to the horizontal movement of the electron beam across the screen, creating the time axis for a waveform display. To achieve this horizontal deflection, a pair of deflection coils (or plates in electrostatic CRTs) is used. One coil provides a magnetic field to pull the beam in one horizontal direction, and the other provides a field to push it in the opposite direction. The sweep amplifier generates the varying signal that drives these two coils, causing the beam to move consistently from left to right. A total of two coils are needed to create the push-pull action for a single axis of deflection. While a CRT typically has four coils (two for horizontal and two for vertical deflection), the sweep amplifier specifically drives only the two coils responsible for the horizontal sweep.

Pass Your FCC Exam!

Study offline, track your progress, and simulate real exams with the GMDSS Trainer app.


Includes Elements 1, 3, 6, 7R, 8, and 9.