Answer
A magnet moves the electrons used to produce an image on a CRT TV away from their intended target.
Work Step by Step
Figure 17–29 shows that the picture is created by accelerating a beam of electrons toward a fluorescent screen. Holding a strong magnet close to the screen exerts a magnetic force on the moving electrons, deflecting them from their intended landing point.
If the field is very strong the picture may go black because all the nearby electrons have been deflected away by the strong magnetic field.
