JAMB - Physics (1982 - No. 19)
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 )
10-2mm
10-3mm
10-4mm
10-5mm
10-6mm
คำอธิบาย
m = Itz
density = \(\frac{\text{mass}}{\text{area x thickness}}\)
Density = \(\frac{Itz}{A \times h}\)
\(10^4 = \frac{0.5 \times 100 \times 60 \times 0.0003}{100 \times h}\)
h = 9 x 10-7cm = 9 x 10-6mm
density = \(\frac{\text{mass}}{\text{area x thickness}}\)
Density = \(\frac{Itz}{A \times h}\)
\(10^4 = \frac{0.5 \times 100 \times 60 \times 0.0003}{100 \times h}\)
h = 9 x 10-7cm = 9 x 10-6mm