磁阻演示管
鋁金屬管長 60 x 4.2cm L x Dia, 管身有一吋分隔長條形孔作觀察窗, 附兩枚小包膠球, 一枚純橡膠, 另一枚是包膠磁性球. 把兩枚小球分別從同一位置放進鋁管中, 你會發現磁性球之下降速度比另一球慢幾倍 (4-5秒)
Item No : JHL 602

ELECTRO-Magnetic resistance demo pipe
This kit can be used to verify Lenz's law and show how strong the electro-magnetic resistance is. T
he effect of the kit is very obvious and wonderful.
The pipe kit consists of following two parts
1. AL pipe with thick wall , 60 x 4.2cm L x Dia. with rectangular windows are evenly arranged along the pipe through which students can watch how two balls fall in the pipe.
2. Two golden rubber balls with 3.2cm dia. and approx. equal weight have the same out-looking. In one of the two balls a cylinder magnet with super strong magnetism-a neodymium magnet-- is contained. Let's call the ball magnet ball
Dropping the balls into the pipe separately, you find that the magnet ball falling in the AL pipe take a longer time (about 4-5 seconds) than the other ball. Why? The reason of the phenomenon, obviously is that the current induced in the pipe wall functions while the magnet ball is falling down through the pipe, the direction of the induced magnetic field is opposite to the direction of the magnetic field of the falling magnet.
參考資料: 高中物理第三冊 第154頁 人教社1997年12月第一版
J.A.M.Clack Magnetic Introduction Experiment, The Physics Teacher Vol 28 No.$ P236 to P238 1990
今日物理Physics Today 第二冊 P.241頁 麥思源博士Dr. SY Mak 香港朗文教育出版社 1995年初版
Item No : JHL 602

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