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Physics for Scientists and Engineers, 6e
Chapter 27 – Current and Resistance
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View Full Document Electric charge is conserved. As a consequence, when current
arrives at a junction of wires, the charges can take either of two
paths out of the junction and the numerical sum of the currents
in the two paths equals the current that entered the junction.
Thus, current is
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a vector
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a scalar
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neither a vector nor a
scalar
The currents in the two paths add numerically to
equal the current coming into the junction, without
regard for the directions of the two wires coming out
of the junction. This is indicative of scalar addition.
Even though we can assign a direction to a current, it
is not a vector. This suggests a deeper meaning for
vectors besides that of a quantity with magnitude and
direction.
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View Full Document Suppose that a currentcarrying ohmic metal wire has a cross
sectional area that gradually becomes smaller from one end of
the wire to the other. The current must have the same value in
each section of the wire so that charge does not accumulate at
any one point. How do the drift velocity and the resistance per
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This note was uploaded on 01/19/2010 for the course PHYS 200 taught by Professor Davies during the Spring '08 term at Roger Williams.
 Spring '08
 Davies
 Charge, Current, Resistance

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