If the refractive index of a medium is \(\sqrt{2}\), what is the critical angle?

In copper plating, a current of 0.5A is allowed for cathode area of 100cm2. If this current is maintained constant for 100 minutes, the thickness of the copper deposited will be approximately (the electrochemical equivalent of copper = 0.0003g/oC, density of copper = 10^4g/cm3 )