Mass of silver to be deposited
=volume×density
=area×thickness×density
Given: Area=80cm2,thickness=0.0005 cm and density=10.5 g/cm3
Mass of silver to be deposited =80×0.0005×10.5
=0.42 g
Applying to silver E=Z×96500
Z=10896500g
Let the current be passed for t seconds.
We know that, W=Z×I×t
So, 0.42=1089600×3×t
or t=0.42×96500108×3=125.09 second.