Why do electrons move in a cathode-ray tube when a strip magnet is brought up to it?

This is due to the fact that a magnetic field acts on electrons with some force. The force with which a magnetic field acts on moving charged particles is called the Lorentz force.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.