28.31.Solve:(a)Let the new current be I′such that I′=2Iwhere Iis the original current. The current densityis JIA=. Since the area of cross section of the wire remains the same, we haveAIJIJ==′′⇒′ =′=JIIJJ2That is, doubling the current doubles the current density.(b)Conduction-electron density is a material’s characteristic value, and does not depend on external factors. Thusn′=n.(c)
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This note was uploaded on 03/14/2009 for the course PHY PHYA22 taught by Professor Abbas during the Spring '09 term at University of Toronto.