Glossary: Faraday's Law & Film-thickness Estimation
术语：法拉第定律与着色膜厚估算
标签：法拉第定律, 膜厚估算, 电流效率, 电化学术语
法拉第第一定律给出电极析出/溶解量 m = M·I·t/(n·F)。对着色中的 Cu→Cu²⁺ 溶解，n=2、M=63.5 g/mol，可由电流与时间反推溶铜量，再按膜层致密度估算 0.2–2 μm 硫化膜厚度；实际电流效率 η 约 60–90%，余量析氢。据此可解释"0.5 A×3 min 与 1.5 A×1 min 色近似但质不同"：累计电量接近则膜厚相近，但大电流成核快、更易局部烧焦发花。
Faraday's first law gives deposited/dissolved mass m = M·I·t/(n·F). For Cu→Cu²⁺ dissolution in coloring (n=2, M=63.5 g/mol), current and time back-calculate copper loss, from which 0.2–2 μm sulfide film thickness is estimated via film density; practical current efficiency η runs 60–90%, the balance evolving hydrogen. This explains why 0.5 A×3 min and 1.5 A×1 min look similar—equal charge, equal thickness—yet the high-current run nucleates faster and burns more easily.