Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

Published by Pearson
ISBN 10: 0321740904
ISBN 13: 978-0-32174-090-8

Chapter 30 - Current and Resistance - Exercises and Problems - Page 888: 32

Answer

$2.3\;\rm mA$

Work Step by Step

We know that the current in the wire is given by $$I=\dfrac{\Delta V_{\rm wire}}{R}$$ and since the wire is connected directly to the two ends of the battery, they have the same potential difference, $V_B=\Delta V_{\rm wire}$ $$I=\dfrac{ V_{\rm B}}{R}\tag 1$$ Now we need to find the resistance of the wire which is given by $$R=\dfrac{\rho L}{A}=\dfrac{\rho L}{\pi r^2}$$ Plug into (1), $$I=\dfrac{ \pi r^2V_{\rm B}}{\rho_{\rm gold} L} $$ $$I=\dfrac{ \pi (0.05\times 10^{-3})^2(0.7)}{(2.4\times 10^{-8})(100)} $$ $$I=\color{red}{\bf 2.3}\;\rm mA$$
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