Magnets and television screens

[serahhhh]

Why do magnets mess up television screens? What is the science behind it?

 

[Integral]

A CRT television creates an image by directing a stream of electrons with electric fields. When you bring magnets near the screen the electrons experience a force which deflects them therefore destroying the image.

 

[mgb_phys]

A moving charged particle creates a magnetic field and similarly a magnetic field creates a force on a moving charged particle.

A TV (at least one with a glass tube, not a Plasma or LCD) works by firing a stream of electrons from a gun at the back to light up the screen. Since electrons are charged the magnetic field bends the beam.

ps. Be careful, most color TVs have a metal sheet just inside the glass to hold the color filter. If you hold a strong magnet too close you can permanently magnetize this sheet and make the picture permanently distorted.