Bending Beams I: Bar Magnets
You're right! The electron beam is directed to shine on different places.
Magnets steer the beam to where it needs to be at different times, and they
also help to focus it. It may be hard to understand how magnets make electrons
move, but the following experiment might clear things up.
In manual mode, use the mouse to drag the magnets around.
Double click on a magnet to reverse polarity.
Warning: magnets will damage your television set!
But that is weird. As you move the magnets closer to the beam of electrons
the beam moves in a direction perpendicular to both the magnet path and the
beam. Why is that?
That's actually a fundamental law of nature. A magnetic field causes a
current of electrons to move at right angles to both the magnetic field (along
the magnet) and the current.