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February 12, 2009
PHY 2054 Discussion Spring ‘09
Conceptual Review: Chapter 17
1.
An electron is circling around a nucleus with a frequency
f
. What is the effective current?
2.
Express number density in terms of Avogadro’s number
N
A
, density and atomic mass
M
.
1.
A steady current is flowing in a resistor
R
. (A resistor is a conductor.) According to the Ohm’s law,
voltage across it is not zero. We already know the potential is constant in a conductor in equilibrium.
What’s wrong?
2. What is the difference between Ohm’s law and the definition of resistance?
C. Resistivity
1. What factors determine the resistance of a conductor?
2. A tension is applied to a wire and the length of the wire is doubled. By what factor does the resistance
of the wire increases?
D. Temperature Variation of Resistance
1. Can you choose the reference temperature on your own?
2. Why does the resistance of many materials increase as its temperature increases?
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This note was uploaded on 12/13/2011 for the course PHY 2054 taught by Professor Avery during the Fall '08 term at University of Florida.
 Fall '08
 Avery
 Physics, Current

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