(一)制作简易小磁针取一颗顶面光亮无痕迹的表面镀铬图钉,将它放在玻璃板上,顶面与玻面接触,切取约1.5厘米长的一段通草(中药店索取)或高梁杆、硬泡塑,将它插在图钉上,然后取一颗大棉线针先在收音机喇叭磁体上进行磁化、然后把针横穿在通草柱上使其平衡、由于光亮图钉与干净的玻璃平面间处于光滑的点接触状态,故在 (1) Making a simple small magnetic needle Take a chrome-plated pushpin with a light surface on the top and place it on a glass plate with the top surface in contact with the glass surface. Cut out a piece of grass about 1.5 cm long (acquired from the pharmacy shop) or sorghum. Rod, rigid foam, insert it on the pushpin, then take a big cotton thread first magnetize on the radio horn magnet, and then cross the needle on the straw to balance it, due to bright pushpin and a clean glass plane In a smooth point contact state, it is