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Resistance
The electrical resistance of a circuit component or device is defined as the ratio of
thevoltageapplied to the electric currentwhich flows through it:
If the resistance is constant over a considerable range of voltage, thenOhm's law, I
= V/R, can be used to predict the behavior of the material !lthough the definitionabove involves "# current and voltage, the same definition holds for the !#
applicationof resistors
$hether or not a material obe%s Ohm's law, its resistance can be described in terms of its bul&
resistivit% The resistivit%, and thus the resistance, is temperature dependent Over siable rangesof temperature, this temperature dependence can be predicted from a temperature coefficientof
resistance
Resistance
The electrical resistance of a circuit component or device is defined as the
ratio of the voltageapplied to theelectric currentwhichflows through it:
If the resistance is constant over a considerable range of voltage, then Ohm's
law, I = V/R, can be used to predict the behavior of the material !lthough
the definition above involves "# current and voltage, the same definition
holds for the !# applicationof resistors
$hether or not a material obe%s Ohm's law, its resistance can be described interms of its bul& resistivit% The resistivit%, and thus the resistance, is
temperature dependent Over siable ranges of temperature, this temperature
dependence can be predicted from a temperature coefficientof resistance
#onductors andinsulators
Resistorcombinations
(on)ohmic resistance: theelectric pic&le
!# behavior of resistor #ommon carbon resistors
Inde*
"##ircuits
+o ac&
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/restmp.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/restmp.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/restmp.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/conins.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/conins.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/sodium.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/sodium.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/rescarb.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/restmp.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elecur.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/restmp.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/conins.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/conins.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/sodium.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/sodium.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/rescarb.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elevol.html#c18/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Resistor Combinations
The combination rules for an% number of resistorsin series or parallel can be
derived with the use of Ohm's 5aw, the voltage law, and the current law
#omparison e*ample
Inde*
"##ircuits
-%per.h%sics0lectricit% and magnetism R Nave+o ac&
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/8/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Resistivity Calculation
The electrical resistanceof a wire would be e*pected to be greater for a longer
wire, less for a wire of larger cross sectional area, and would be e*pected to
depend upon the material out of which the wire is made 6resistivit%70*perimentall%, the dependence upon these properties is a straightforward one
for a wide range of conditions, and the resistance of a wire can be e*pressed as
Resistance= resistivit%* length/area
8or a wire of length L= m = ft
and area A= cm9
corresponding to radius r= cm
and diameter inches for common wire gaugecomparison
with resistivit% = 3 = * 2; ohm meters
will have resistance R= ohms
0nter data and then clic& on the 29 copper wire pon changes, the values will not be forced to beconsistent until %ou clic& on the
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The factor in the resistance which ta&es into account the nature of the materialis the resistivit% !lthough it is temperature dependent, it can be used at a
given temperature to calculate the resistance of a wire of given geometr%
"iscussion Table of resistivities #ommon wire gauges
-%per.h%sics0lectricit% and magnetism R Nave+o ac&
DC Circuit Examples
Thebasic toolsfor solving " # circuit problems are Ohm's 5aw, thepowerrelationship, the voltage law, and the current law The following configurations
are t%picalG details ma% be e*amined b% clic&ing on the diagram for the desired
circuit
Inde*
"##ircuits
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c5http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c5http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c18/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
Two Loop Circuits
! circuit with two loops and two sources is involved enough to illustratecircuit anal%sis techni
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Current Law and Flowrate
8or an% circuit, fluid or electric, which has multiple branches and parallelelements, the flowrate through an% cross)section must be the same This is
sometimes called the principle of continuit%
$ater analog% to "# circuits Voltage law #urrent law
Inde*
"##ircuits
-%per.h%sics0lectricit% and 4agnetism R Nave +o ac&
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Voltage Law and Pressure
$ater analog% to "# circuits Voltage law #urrent law
Inde*
"#
#ircuits
-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
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!m"s Law#Poiseuille"s Law
Ohm's lawfor electric current flow and .oiseuille's lawfor the smooth flow of
fluids are of the same form
$ater analog% to "# circuits
Inde*
"#
#ircuits
-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
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'asic DC Circuit Relations!ips
"# circuits can be
completel%
anal%ed with
these four
relationships
Ohm's law I = V/R
.owerrelationship
. = VI
Voltage 5aw
The net voltage change ise
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"ata can be entered into an% of the bo*es below ?pecif%ing an% two of the
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The voltage law is one of the main tools for the anal%sis of electric circuits,along with Ohm's 5aw, the current lawand thepower relationship !ppl%ing
the voltage law to the above circuits along with Ohm's law and the rules for
combining resistorsgives the numbers shown below The determining of thevoltages and currents associated with a particular circuit along with the power
allows %ou to completel% describe the electrical state of a direct current circuit
#urrent law Resistor combinations
!nalog% in water circuit
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/elepow.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c28/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
Current Law
The electric currentin amperes that flows into an% Hunction in an electric circuitis e
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Voltage law Resistor combinations
!nalog% in water circuit
-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#emconhttp://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#emconhttp://history.go%28-1%29/8/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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!m"s Law
8or man% conductorsof electricit%, the electric currentwhich will flow through
them is directl% proportional to the voltageapplied to them $hen a microscopic
view of Ohm's lawis ta&en, it is found to depend upon the fact that the driftvelocit% of charges through the material is proportional to the electric field in
the conductor The ratio of voltage to current is called the resistance, and if theratio is constant over a wide range of voltages, the material is said to be an
JohmicJ material If the material can be characteried b% such a resistance, then
the current can be predicted from the relationship:
"ata can be entered into an% of the bo*es below ?pecif%ing an% two of the
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Voltage Law
The voltagechanges around an% closed loop must sum to ero (o matter what
path %ou ta&e through an electric circuit, if %ou return to %our starting point %ou
must measure the same voltage, constraining the net change around the loop tobe ero ?ince voltage is electric potential energ% per unit charge, the voltage
law can be seen to be a conse
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#urrent law Resistor combinations
!nalog% in water circuit
-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#emconhttp://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/watcir2.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#emconhttp://history.go%28-1%29/8/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Current Law
The electric currentin amperes that flows into an% Hunction in an electric circuit
is e
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Voltage law Resistor combinations
!nalog% in water circuit
-%per.h%sics0lectricit% and 4agnetism R Nave+o ac&
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Resistivity and Conductivity
The electrical resistance of a wire would be e*pected to be greater for a longer
wire, less for a wire of larger cross sectional area, and would be e*pected to
depend upon the material out of which the wire is made 0*perimentall%, thedependence upon these properties is a straightforward one for a wide range of
conditions, and the resistance of a wire can be e*pressed as
The factor in the resistance which ta&es into account the nature of the materialis the resistivit% !lthough it is temperature dependent, it can be used at a
given temperature to calculate the resistance of a wire of given geometr%
The inverse of resistivit% is called conductivit% There are conte*ts where the
use of conductivit% is more convenient
0lectrical conductivit% = 1 = 2/3
Calculati
on
Table of
resistivities
Common wire
gauges
Microscopic view of
resistivity
Index
HyperPhysics*****Electricity and magnetism R
Nave
o !ac"
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c4http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c4http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmmic.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmmic.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c4http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c4http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/rstiv.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/Tables/wirega.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmmic.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmmic.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/8/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Resistor Combinations
The combination rules for an% number of resistorsin series or parallel can be
derived with the use of Ohm's 5aw, the voltage law, and the current law
Comparison
example
Index
#C
Circuit
s
HyperPhysics*****Electricity and magnetism RNave
o
!ac"
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://history.go%28-1%29/http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/ohmlaw.html#c3http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dcex3.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.htmlhttp://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dccircon.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html#hphhttp://hyperphysics.phy-astr.gsu.edu/Hbase/emcon.html#c1http://history.go%28-1%29/http://history.go%28-1%29/8/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Resistivity Calculation
The electrical resistance of a wire would be e*pected to be greater for a longer wire, less
for a wire of larger cross sectional area, and would be e*pected to depend upon the
material out of which the wire is made 6resistivit%7 0*perimentall%, the dependence uponthese properties is a straightforward one for a wide range of conditions, and the resistance
of a wire can be e*pressed as
$esistance% resistivityx
length&area
'or a wire of length L
% m % ft
and area A% cm(
corresponding to radius r% cm
and diameter inches for common wire gaugecomparison
with resistivity % ) % x +, ohm meters
will have resistance R% ohms-
0nter data and then clic& on the 29 copper
wire pon changes, the values will not be forced to be consistent until %ou clic& on the
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(ncreasing Current in Coil
Increasing current in a coil of wire will generate acounter emfwhich opposes the current !ppl%ing the
voltage lawallows us to see the effect of this emf on
the circuit e
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(nductor AC Response
Impedanc
e
Calculate
Examine
Capacit
or
$esistor
Contribution to
compleximpedance
Phasordiagram
Lou &now that the voltage across an inductor leads the current because the 5en' law behaviorresists the buildup of the current, and it ta&es a finite time for an imposed voltage to force thebuildup of current to its ma*imum
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/imped.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/imped.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acind.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/accap.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/accap.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/impcom.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/impcom.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/phase.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/phase.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/imped.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/imped.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acind.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/accap.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/accap.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/acres.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/impcom.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/impcom.html#c1http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/phase.html#c2http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/phase.html#c28/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Capacitors
#apacitance is t%pified b% a parallel plate
arrangement and is defined in terms of charge
storage:
where
= % magnitude of chargestored oneach plate-
> % voltageapplied to the plates-
Air Tan% Analogy )or a Capacitor
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elecur.html#c2http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elecur.html#c2http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.html#c18/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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Airtan% Analogy to C!arging a Capacitor
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C!arging a Capacitor
$hen a batter% is connected to a series resistorandcapacitor, the initial current is high as the
batter% transports charge from one plate of the capacitor to the other The charging current
as%mptoticall% approaches ero as the capacitor becomes charged up to the batter% voltage#harging the capacitor stores energ% in the electric fieldbetween the capacitor plates The rate of
charging is t%picall% described in terms of a time constantR#
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capeng.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/filter.html#c2http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capeng.html#c1http://hyperphysics.phy-astr.gsu.edu/hbase/electric/filter.html#c28/11/2019 Unit 1 (Resistance,Capacitance,Inductance)
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*toring Energy in a Capacitor
Theenerg% storedon a capacitor can bee*pressed in terms of the wor& done b% thebatter%Voltagerepresents energ% per unit
charge, so the wor&to move a charge element d