https://blog.gongquiz.com/2022/08/07/%eb%8b%a4%ec%9d%8c-%ec%a4%91-2%ea%b0%9c%ec%9d%98-%ec%a0%84%ea%b7%b9anode%ec%99%80-cathode-%ec%82%ac%ec%9d%b4%ec%97%90-%ec%82%bd%ec%9e%85%eb%90%9c-%ec%9c%a0%ea%b8%b0%eb%ac%bc-%ec%b8%b5%ec%97%90/