Electrical Circuits
-
Upload
walt-sautter -
Category
Education
-
view
11.986 -
download
1
description
Transcript of Electrical Circuits
W. Sautter 2007
The next slide is a quick promo for my books after which the presentation will begin
Thanks for your patience!Walt S.
[email protected] stuff at: www.wsautter.com
Books available at:www.wsautter.com
www.smashwords.comwww.amazon.com
www.bibliotastic.comwww.goodreads.com
Walt’s Books for Free!
AMPS
volts
Ammeters measurecurrent in amperes
and are alwayswired in series in
the circuit.
Voltmeters measurepotential in voltsand are always
wired in parallel in the circuit.
wiring
battery
voltmeter
ammeter
resistance
capacitor
+ -
A
V
junction
terminal
AC generator
Variableresistance
Variablecapacitor
ELECTRON PUMP
(SOURCE VOLTAGE)[ENERGY IN]
LOAD(RESISTANCE)[ENERGY OUT]
CONDUCTOR
ELECTRONSOUT OF SOURCE
ELECTRONSOUT OF LOAD
ELECTRONSBACK TOSOURCE
ELECTRONSINTOLOAD
HIGHER ENERGY ELECTRONS LOWER ENERGY ELECTRONS
CONDUCTOR
PotentialIn volts
(joules / coul)
CurrentIn amperes
(coul / second)
ResistanceIn ohms
(volts / amp)
Drop across a resistance
Current passingThrough the
resistor
volts
Battery current
Electrons haveLess Energy
Electrons haveMore Energy Electrons get
An energy boost
current
volts
Resistor current
Electrons haveMore Energy
Electrons haveLess Energy Energy is lost
In the resistor
There are three generally types of electrical circuits:
(1) Series circuits in which the current created by the voltagesource passes through each circuit component in succession.
R2 A2
R 1
R 3
A1
Arrows showCurrent pathThrough each
component
(2) Parallel circuits in which the current created by the voltagesource branches with some passing through one component andwhile the rest of the current passes through other components.
Arrows showCurrent pathThrough each
component
Junction or Branching points
A1R1
R2
R3
A2
A3
A4
R 4
(3) Series Parallel circuits or combination circuits
which contain series segments and parallel
segments.
R1
R2
R3
A1
A2
A3
A4
R 4
SERIES
PARALLEL
Arrows showCurrent pathThrough each
component
All electrical circuit analysis requires the useof two fundamental laws called
Kirchhoff’s Laws
FIRST LAWAll current entering a junction point must equal all current leaving that junction point
Junctionpoint
Current Entering ( I1 )
Current Leaving ( I2 )
Current Leaving ( I3 )
I1 = I2 + I3
SECOND LAWAround any complete loop, the sum of the
voltage rises must equal the sum of voltage drops
Battery(voltage rise)
Resistance 1(voltage drop 1)
Resistance 2(voltage drop 2)
Resistance 3(voltage drop 3)
Current flow
Complete loop
V(Battery) = V1 + V2 + V3
+ -
R2
R1
A2
A1
At
V1
EMF
Kirchhoff’s Laws Around a loop
V rises = V dropsA loop is a completedPath for current flow
Battery
V2
Loop #1
Loop #2
Loop #3
+ -
Complete currentPaths in a circuit
When using Kirchhoff’s laws we apply the principlesof conventional current flow.
When current leaves the positive (+) terminal of a voltage source and enters the negative (-) terminal
a voltage rise occurs across the source. If the current enters the positive and exits the negative a of a voltage
source a voltage drop occurs across the source.
When tracing a current loop, if the assumed directionof the current and the loop direction are the same,
a voltage drop occurs across a resistance.If the assumed direction of the current and the
loop direction are opposite, a voltage rise occursacross the the resistance.
Battery( 6 volts)
+ -
CurrentflowV = + 6 v
Currentflow
V = - 6 v
When using Kirchhoff’s laws we apply the principlesof conventional current flow.
When current leaves the positive (+) terminal of a voltage source and enters the negative (-) terminal
a voltage rise occurs across the source.
If the current enters the positive and exits the negative a of a voltage source a voltage drop occurs across
the source.
When tracing a current loop, if the assumed directionof the current and the loop direction are the same,
a voltage drop occurs across a resistance.
resistor
V = + 6 vA voltage
rise
AssumedCurrent flow
V = - 6 vA voltage
drop
Loopdirection
AssumedCurrent flow
Loopdirection
If the assumed direction of the current and theloop direction are opposite, a voltage rise occurs
across the the resistance.
Series ResistanceRt = R1 + R2 + ….
EMF = V1 + V2 + V3 + Vi
In a series circuit:(1) The total resistance of the circuit is the sum of
the resistance values in the circuit.
(2) The sum of all voltage drops across the resistorsin the circuit equals the voltage rise of the source.
The through each resistance is the same.
I TOTAL = I1 = I2 = I3 = Ii
R2 A2
V2
R 1EMF
Ri
R 3
V1
V3
A1
R = ResistanceIn ohms
VoltmetersIn parallel
AmmetersIn series
Series ResistanceRt = R1 + R2 + ….
Ammeters readThe same everywhere
In the circuitA1 = A2
EMF = V1 + V2 + V3 + Vi
In a parallel circuit:(1) The reciprocal of the total resistance of the circuit is the sum
of the reciprocals of the resistance values in the circuit.
Parallel Resistance1/Rt = 1/R1 + 1/R2 ….
(2) The sum of the voltage drops across the resistors in a branch of the circuit equals the voltage rise of the source.
V source= V1 = V2 = V3 = Vi
(3) All current entering a junction = all currentleaving the junction
I TOTAL = I1 + I2 + I3 + Ii
R1
R2
R3
A1
A2
A3
A4
V2
V3
EMF
V1
Parallel Resistance1/Rt = 1/R1 + 1/R2 ….
Kirchhoff’s Laws(1) All current enteringA junction = all current
Leaving the junction(2) Around a loop
V rises = V drops
Junctionpoints
VoltmetersIn parallel
AmmetersIn series
BatteryR = Resistance
In ohms
R1
R2
R3
A1
A2
A3
A4
V1
R 4V4
V2
V3
EMF
Ri
PARALLEL
SERIES
Parallel Resistance1/Rt = 1/R1 + 1/R2 ….
Series ResistanceRt = R1 + R2 + ….
Kirchhoff’s Laws(1) All current enteringA junction = all current
Leaving the junction(2) Around a loop
V rises = V drops
resistors
capacitors
Integratedcircuits