Here's why:
* Cathode rays are streams of electrons. These electrons are negatively charged particles.
* Magnets create magnetic fields. These fields exert a force on moving charges.
* The direction of the force on a moving charge depends on the direction of the magnetic field and the direction of the charge's motion. This is described by the right-hand rule.
Therefore, when you reverse the magnet's orientation, you reverse the direction of the magnetic field. This in turn reverses the direction of the force on the cathode rays, causing them to deflect in the opposite direction.
In simpler terms, think of it like this:
* The magnet acts like a "guide" for the cathode rays.
* If you flip the magnet, you flip the guide, and the rays follow the new direction.
