Electro-chemical machining is performed on a flat copper workpiece. If the material removal rate is \(2\ cm^3/min\) throughout the process, then the required current (in A) is ______ . (Rounded off to 1 decimal place) Copper properties: Melting point = \(1085 °C\), density = \(9\ g/cm^3\), gram atomic weight = \(63\), and valency of dissolution = \(2\) Faraday's constant = \(96500 C\) Stefan-Boltzmann constant = \(5.67 \times 10^{-8} W/m^2-K^4\)