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10th Class Science Electricity and Circuits Question Bank Electricity

  • question_answer
    How long would it take a current to 10 amperes to put a layer of copper \[0.\text{1}\] mm thick on both sides of a rectangular plate of \[\text{1}0\text{ cm }\times \text{ 1 }\times \text{ 65}\] cm (e.c.e. of copper\[=\text{ }0\text{ }\times \text{ }000\text{33 gm}/\text{coul}\], density of Copper\[=\text{ 9 gm}/\text{cc}\])?

    A)  9 sec

    B)  9 min

    C)  900 sec  

    D)  900 min

    Correct Answer: C

    Solution :

     Mass of copper deposited\[=\]Volume \[\times \] Density                     \[=10\times 1.65\times \frac{0.1}{10}\times 9\] Time taken for deposition,                  \[t=\frac{m}{zi}=\frac{10\times 1.65\times 0.1\times 9}{10\times 0.0033\times 10}\sec \]                    \[=\,\,\mathbf{450}\] sec. Since, above is the time for copper deposition on one side, therefore time taken for both sides \[=2\times 450=\mathbf{900sec}\].


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