19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a...
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Transcript of 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a...
![Page 1: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/1.jpg)
19 Current, Resistance, & DC Circuits
![Page 2: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/2.jpg)
Electric Current
Current: net charge passing through a cross-section per unit time.Units: Ampere (A), 1 A = 1C/s (mA, A, nA, pA)Scalar , Positive current=flowing direction of positive charges
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QI
![Page 3: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/3.jpg)
Resistance and Ohm’s Law
R: resistance, L: length, A:cross section, : resistivityUnit(R): Ohm(), 1= 1V/A; Unit(): ohm.meter (.m)
Temperature dependence: RT = R0[1+(T-T0)]T in Celsius, R0 = R(T=T0=20oC): temperature coefficient (0.003~0.005 oC-1)
A
LRor
A
LR
IRVI
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VIVI
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L
A
![Page 4: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/4.jpg)
Resistivities of Different Materials
![Page 5: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/5.jpg)
Superconductivity & Non-ohmic Conductors
![Page 6: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/6.jpg)
Electromotive Force & Circuits
A pump is needed to keep the water circulatingpump~electromotive force (emf)
Circulating without pumpNo emf~imposiple
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emf Source ()
Terminal voltage:Vab = Vab = = IR (ideal emf)
Vab = r (with internal resistance, r)
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Voltage and Current Measurements
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Potential drops and rises in circuit
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Power: the energy consumed per unit time.
Power Output of a Source
Ir2 is the energy dissipated inside the sourceheat
Energy and Power in Electric Circuits
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WP
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rIIIrIIVP 2)(
![Page 11: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/11.jpg)
Resistors in Series & Parallel
(in series)
(in parallel)...1111
...
321
321
RRRR
RRRR
eq
eq
![Page 12: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/12.jpg)
Combinations
![Page 13: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/13.jpg)
Kirchhoff’s Rules
Junction Rule
Loop Rule
0 I
0V
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Kirchhoff’s Rules
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Electrical Measuring Instruments
AmmetersGalvanometer
Voltmeters
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Resistance-Capacitance Circuits and Transient Effects
RC
t
RC
t
eQqeIiC
qiR 100
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Summary: Current
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Summary: Resistance & Ohm’s Law
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Summary: emf
![Page 20: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/20.jpg)
Summary: Energy & Power
R
VRIIV
t
QV
t
WP
22
rIIIrIIVP 2)(
![Page 21: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/21.jpg)
Summary: Resistors in Parallel & Series
(in series)
(in parallel)...1111
...
321
321
RRRR
RRRR
eq
eq
![Page 22: 19 Current, Resistance, & DC Circuits. Electric Current Current: net charge passing through a cross-section per unit time. Units: Ampere (A), 1 A = 1C/s.](https://reader036.fdocuments.net/reader036/viewer/2022062305/56649eea5503460f94bfb7f9/html5/thumbnails/22.jpg)
Summary: Kirchhoff’s Rules
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Summary: Charging & Discharging
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HomeworkCh19: 1, 5, 7, 12, 24, 31, 33, 42, 48, 52, 57, 61, 63
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Problem 57
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Problem 61
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Problem 52 & 53