Physics: Principles with Applications (7th Edition)

Published by Pearson
ISBN 10: 0-32162-592-7
ISBN 13: 978-0-32162-592-2

Chapter 18 - Electric Currents - Questions - Page 520: 20

Answer

See work below.

Work Step by Step

Use equation 18-10 to answer these questions. $$I=neAv_d$$ This leads to $$v_d=\frac{I}{neA}$$ a. If the length doubles, the wire’s resistance doubles. The current I will be reduced by a factor of 2, and so will the drift velocity. b. If the radius doubles, the area goes up by a factor of 4, but so does the current, I, so the drift velocity is unchanged. This is just like putting 4 identical wires in parallel – we wouldn’t expect the drift velocity to change. c. If V doubles while the resistance remains constant, then the current also doubles. Using equation 18-10, we see that the drift velocity also doubles.
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