{"resolved":true,"match_type":"uuid","source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","requested_by":"printed_page","book":{"source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","id":"38270854-596f-4a26-8183-db8c968c6020","uuid":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","normalized_title":"编码隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","isbns":["9787121181184","0123456789","6044921875","3039331000","0000000000","0000000000000"],"parsed":true,"ai_readable":true,"document_type":"book","page_count":438,"navigation_url":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020","title_url":"https://workshop.closeclaw.top/ai/title/%E7%BC%96%E7%A0%81%20%E9%9A%90%E5%8C%BF%E5%9C%A8%E8%AE%A1%E7%AE%97%E6%9C%BA%E8%BD%AF%E7%A1%AC%E4%BB%B6%E8%83%8C%E5%90%8E%E7%9A%84%E8%AF%AD%E8%A8%80","fixed_page_url_template":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","path_api_url_template":"https://workshop.closeclaw.top/api/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","read_url":"https://workshop.closeclaw.top/api/ai/read/38270854-596f-4a26-8183-db8c968c6020","page_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/page","search_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/search"},"page":{"printed_page":29,"pdf_page":45,"physical_index":45,"physical_index_base":0,"printed_page_status":"recognized","page_sha256":"4bc36356ecc09b246ab2d8961248524085ebe9d648f2bde6cac54d0d6ee3163b"},"chapter":"编码隐匿在计算机软硬件背后的语言","content":"$$\nI { = } E / R\n$$\n\n其中，I用来表示电路中的电流，E用来表示电压（它代表电动势)，R表示电阻。\n\n例如，下面这节电池是单独放置的，没有连接任何设备。\n\n它的电压E是1.5伏。它代表做功的势能，但是因为正负极通过空气也有连通，所以电阻（R所代表的物理量）非常非常大，也就是说，电流（I）等于1.5伏的电压除以一个极大的数。因而电流在这里几乎是0。\n\n现在我们用一小段铜线把正负极连接起来（从现在开始，我们不再在示意图上画导线的绝缘层)。\n\n这种情形被称为“短路”。电压仍然是1.5伏，但是现在的电阻非常非常小。现在的电流等于1.5伏的电压除以一个非常小的电阻值。也就是说电流将变得非常非常大。大量的电子流经导线。在现实情况下，电流会因为电池的型号大小而受到限制。电池或许无法导通如此大的电流，且实际电压也将低于1.5伏。如果电池足够大的话，导线将会发热，因为电能被转化成了热能。如果导线继续变得很热，它将会发光甚至熔化。\n\n大部分的电路都介于这两种极端情况之间。我们可以把它们统一表述为如下图所示。\n\n4 手电筒的剖析\n\n29","previous_page":28,"next_page":30}