燈柱下的黃色盒子,拍一拍便會着燈,但係佢點樣感應隻手拍落去呢?
係唔係感應推力呢?但係用手指甲去彈彈極都唔着.
係唔係感應熱力呢?但係用衫袖都禁得着.
究竟紅綠燈感應器係用咩原理呢???
收錄日期: 2021-04-13 16:58:54
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091214000051KK01296