This preview shows pages 1–12. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Chapter 25 Electric Currents and
Resistance Ccowght «1 20L“.J Pomsm [ducallu IIIIII L. 252 Electric Current By convention, current is defined as flowing from + to . Electrons actually flow in the
opposite direction, but not all currents consist
of electrons. meentionul Electron
current ﬂow lilcclron currcnl C w titi‘ICICElPoatsanﬁllcannnIn: wcrhx! Sm( Maul $6 915‘: 254 Resistivity For any given material, the resistivity
increases with temperature: Pr — p.;.[l + «('1' * 1,311]. Semiconductors are complex materials, and may have resistivities that decrease with
temperature. 253 Ohm’s Law: Resistance and
Resistors In many conductors, the
resistance is independent
of the voltage; this
relationship is called
Ohm’s law. Materials that do not follow Ohm’s law
are called nonohmic. Unit of resistance:
the ohm, Q: 1 o = 1 WA. Consider two identical resistors wired in se
ries (one behind the other). If there is an
electric current through the combination.
the current in the second resistor is 1. equal to
2. half 3. smaller than, but not necessarily half the current through the ﬁrst resistor. 255 Electric Power What you pay for on your electric bill is
not power, but energy  the power
consumption multiplied by the time. We have been measuring energy in joules,
but the electric company measures it in
kilowatthours, kWh: 1 kWh = (1000 W)(3600 s) = 3.60 x 106 J. ...
View
Full
Document
This note was uploaded on 10/20/2010 for the course PHY 2445 taught by Professor Heo during the Spring '10 term at NE Texas CC.
 Spring '10
 heo

Click to edit the document details