Скачать или смотреть MIT Physics Demo -- Magnetic Deflection of a TV Image

An cathode ray tube (CRT) television is connected to a video camera.

When a strong magnet is brought close to the television screen, the image becomes warped and discolored.

While many new televisions use flat screen technology, older CRTs produced images by firing electron guns (one red, one green, one blue) through the television body onto the back of the screen.
When a magnet is brought close to the screen, it deflects the paths of the electron beams and distorts the picture.

A strong enough magnetic field can even create a hole in the electron beams, causing a black spot on the picture.

This TV has been subject to many magnet encounters, which has permanently damaged the picture.

Source: http://techtv.mit.edu/file/1182