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Thermal and Chemical Effect of Current — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsThermal and Chemical Effect of Current2 Marks
Question
A brass plate having surface area 200cm2 on one side is electroplated with 0·10mm thick silver layers on both sides using a 15A current. Find the time taken to do the job. The specific gravity of silver is 10.5 and its atomic weight is 107.9 g/mol.
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Answer

I = 15A
Surface area = 200cm2,
Thickness = 0.1mm
Volume of Ag deposited = 200 × 0.01 = 2cm3 for one side
For both sides, Mass of Ag = 4 × 10.5 = 42g
$\text{Z}_{\text{Ag}}=\frac{\text{E}}{\text{F}}=\frac{107.9}{96500}$
$\text{m}=\text{ZIT}$
$\Rightarrow42=\frac{107.9}{96500}\times15\times\text{T}$
$\Rightarrow\text{T}=\frac{42\times96500}{107.9\times15}=2504.17\text{sec}=41.73\text{min}\approx42\text{min}$

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