Faraday's First Law of Electrolysis
The mass of a substance liberated at an electrode is directly proportional to the quantity of electricity passed.
Formula / equation
m = Z I t
Unit
g
In depth
Since charge equals current multiplied by time, doubling either doubles the mass deposited. The law follows directly from the fact that a fixed number of electrons is required per ion discharged, and it makes electrolysis a precise way of measuring charge.
Examples in the real world
Passing 2 A for 30 minutes deposits twice as much copper as the same current for 15 minutes.