Question

How long would it take a current of $10A$ to put a layer of copper $0.1mm$ thick on both sides of a rectangular plate of $10cm\times 1.65cm$ (e.c.e. of copper $=0.00033gm/C,$ density of copper $=9gm/cc)?$

• A. $9sec$
• B. $9min$
• C. $900sec$
• D. $900min$

Answer 1

The correct option is C $900sec$

Given : $Z=0.00033gm/C$ $\rho =9gm/cc$

Size of the rectangular plate is given as $10cm\times 1.65cm$.

Area of the plate $A=10\times 1.65$ $c{m}^2=16.5$ $c{m}^2$

Total thickness of copper to be deposited (on both sides) $t=2\left(0.1\right)mm=0.02cm$

Thus total volume of copper deposited $V=tA=0.02\times 16.5=0.33$ $c{m}^3$

Weight of copper deposited $W=\rho V=9\times 0.33$ $gm$

Time taken $t=\frac{W}{Zi}$

$⟹$ $t=\frac{9\times 0.33}{0.00033\times 10}=900$ seconds