為甚麼磁石可以干擾電視機？

Question

為什麼磁石可以干擾電視機？

圖片：http://hk.geocities.com/ac0004_7019/magnet/magnet_tv_1.JPG
　　　( 中間黑點是強力磁石，不同顏色又代表甚麼？)

影片：http://hk.geocities.com/ac0004_7019/magnet/magnet_tv_2.AVI


對LCD屏幕無效，何解？

看看那圖片和影片，很精彩的 ~

Answer 1

熒光屏有色是因爲熒光屏有電子槍把電子射到熒光屏的不同的熒光粉上。而負責把電子加速的電子槍，利用電磁吸引，把電子加速和改變軌跡。所以儅你用磁石靠近電視機，會影響電子射擊的軌道，打在錯誤的熒光粉上，形成不同的顔色。


而LCD屏幕，中文叫液晶，是一種特殊的液體(常溫下是晶體),通電后會發出光。不同液晶，不同電阻，產生不同顔色的光。細心發現，LCD屏幕是由許多一點點組成，一點點裏面就是液晶。
試用手指擠壓LCD屏幕，會有水波一樣的感覺。現在用的計算機，雖然是黑白，但同屬液晶。

LCD屏幕不用到電磁，所以不受干擾

2007-03-04 19:15:16 補充：
這個我小時候玩過，不過只是一塊，不是全屏。那時真的嚇死我，以爲弄坏了，好在之後沒事。

2007-03-04 19:18:47 補充：
中間黑點可能強的磁鐵把電子全反彈了，沒擊在屏幕上。不同顔色沒什麽太大關係

Answer 2

The picture we see on conventional TV screen is formed by bombardment of electrons emitted from an electron gun at the back of the cathode ray tube (CRT) in the TV set.

Magnetic field from the magnet will divert the electrons and disturb their intended trajectory, hence they will strike at different places on the screes instead of the usual places in forming a TV picture . The pattern shown on the movie is actually the magnetic field pattern of the magnet.

Since colour TV employs three eelctron guns respectively for the production of the three primary colours (red, blue and green) and the speeds of electrons emitted from the three electron guns may not be the same, this is why the three colours are seen separated on the screen under the influence of the magnet.

LCD screen is a solid state device which doesn't use electron beam to work. Therefore, they are not influenced by a nearby magnet.