8/14/2019 Electrical Circuit Behavior
1/22
1
Electrical Circuit Behavior
Section III
In this Section we will introduce the following information:
Theory behind Circuit Behavior Construction of all circuits Series Circuit Behavior
Parallel Circuit Behavior Series/ Parallel Circuit Behavior Introduction to Meter Application in Circuits
8/14/2019 Electrical Circuit Behavior
2/22
8/14/2019 Electrical Circuit Behavior
3/22
3
Series Circuits
wwww
--------
------
----
Battery
fuse
Load 1
wwww
Load 2
Series Circuit Rules
1. The Resistance Totalwill always be
equal to the sum of all of the loadresistances in the circuit.
2. The total circuit Voltage Dropwillalways be equal to the applied source
voltage.However, each load will havea different voltage drop based on itsindividual resistance value.
3. The Current flowin the the circuit
is the same regardless of where itis measured.
A Series Circuit is considered a Voltage Dividing Circuit
8/14/2019 Electrical Circuit Behavior
4/22
4
Series Circuits
wwww
--------
------
----
Current is the same everywhere
Resistance Total is the sum
of each load resistance
Voltage Drop across the total circuitequals the applied source voltage
Battery
fuse
Load 1
wwww
Load 2
2 Ohms2 Ohms
2 Ohms + 2 Ohms = 4 Ohms Total
RT= The sum of all Resistance
8/14/2019 Electrical Circuit Behavior
5/22
5
Series Circuits
6 Volts + 6 Volts = 12 Volt Voltage Drop
--------
------
----
Vdr= Voltage DropVoltage drop equals the applied
source voltage.This is the voltageconsumed or used by the circuitcomponents or resistors.
Current is the same everywhere
Resistance Total is the sum of each loadresistance
Voltage Drop across the total circuit equalsthe applied source voltage
--------
------
----
wwww
Battery
fuse
Load 1
wwww
Load 2
12 Volts 12 Volts
12 Volts12 Volts
6 Volts6 Volts
12 Volts
8/14/2019 Electrical Circuit Behavior
6/22
6
Series Circuits
--------
------
----
wwww
Battery
Load 1
4 Ohms
12Volts
--------
------
----
It= Intensity TotalThis refers to the total current
(amps) flow through the circuit.
Current is the same everywhere
Resistance Total is the sum of each loadresistance
Voltage Drop across the total circuit equals
the applied source voltage
3 Amps
12 Volts 4 Ohms = 3 Amps
Note: When calculating Amps, an ammeteris placed in series with the circuit.
3 Amps
8/14/2019 Electrical Circuit Behavior
7/22
7
wwwwww
R1
3 Ohms
12Volts
Amps ?
Volts R1 = ? Amps12 Volts 3 Ohms = 4 Amps
Series Circuits
E
? R
Using Ohms Law calculate the amountof amp flow in the circuit below
E = VoltsR = OhmsI = Amps
8/14/2019 Electrical Circuit Behavior
8/22
8
Volts R1 + R2 = ? Amps6 Ohms + 4 Ohms = 10 Ohms
12 volts 10 Ohms = 1.2 Amps
wwwwww
R1
6 Ohms
12Volts
Amps ?
wwwwww
R24 Amps
E
? R
Series Circuits
E = Volts
R = OhmsI = Amps
Using Ohms Law calculate the amountof amp flow in the circuit below
8/14/2019 Electrical Circuit Behavior
9/22
9
wwwwww
R1
? Ohms
12 Volts
10 Amps
Volts Amps = Resistance
12 Volts 1.2 Amps = 10 OhmsE
I ?
Series Circuits
E = Volts
R = OhmsI = Amps
Using Ohms Law calculate the amountof resistance in the circuit below
8/14/2019 Electrical Circuit Behavior
10/22
10
Series Circuit Review
Ohms Law can be applied to a series circuit to find unknownvalues as long as you have at least two of values required towork the formula and, you remember the following rules for a
seriescircuit.
1. Since there is only one path for current to flow through,current througheach load(resistance) is the same regardless of the number of loads in
the circuit or where the current is measured in the circuit.
2. The total resistance in the circuit will equal to the sum of the individualload resistances in the circuit.
3. The voltage drop at each load will vary depending on its resistance,however, the total voltage drop will be equal to the applied sourcevoltage.Source voltage is divided completely by all the loads, thereforea Series Circuit is referred to as a Voltage Dividing Circuit.
8/14/2019 Electrical Circuit Behavior
11/22
11
Parallel Circuits
Parallel CircuitA parallel circuit has two or more pathsfor current to flow through. Theamount of current through eachbranch is determined by the loadresistance of each branch. If the circuitis broken after a load, only that loadwill cease to operate.
8/14/2019 Electrical Circuit Behavior
12/22
12
ww
ww
w w
w w 12
volts4 4
R1 R2
Parallel Circuits
12volts
12volts
Parallel Circuit Rules
1.The source voltageand the voltageapplied to or measured across each loadresistance is the same.
2.The current through each load is
determined by its resistance.
3. The resistance totalof the circuit willalways be less than the lowest resistancein the circuit.
4. The total currentin the circuit will beequal to the sum of the branch currentsthrough each individual load.
A Parallel Circuit is considered a Current Dividing Circuit
8/14/2019 Electrical Circuit Behavior
13/22
13
Source Voltage(Sv) is the same thruboth loads.
Resistance Total(Rt) will be less than
lowest value of individual resistor.
The Total Current (It) in the circuit willequal the sum of the branch current flow
R2
I = V / R
12 v/ 2 = 6 amps
E
? R
wwww
w w w w
12volts
4
2
R1 R2
Parallel Circuits
R1
I = V / R
12 v/ 4 =3 amps
E= Electromotive Force (EMF) or VoltsR= Resistance or Ohms ( )
I = Intensity of Current (quantity), (A),or amps (short for amperage)
Load resistance determines
current through each load
14
8/14/2019 Electrical Circuit Behavior
14/22
14
Rt = (R1 X R2) / (R1 + R2)
(4 X 2)=8 / (4+2)=6
8 /6 = 1.33 ohms
Parallel Circuits
E
I R
wwww
w w w w
4
2
R1 R212
volts
Source Voltage(Sv) is the same thru
both loads.
The Total Current (It) in the circuit willequal the sum of the branch current flow.
NOTE: Individual resistor value does not
matter in a parallel circuit, only whencalculating current flow thru one load usingohms law does it matter.
E= Electromotive Force (EMF) or Volts
R= Resistance or Ohms ( )I = Intensity of Current (quantity), (A ),
or amps (short for amperage)
Total Circuit Resistance willalways be less than the
lowest individual resistancein the circuit.
15
8/14/2019 Electrical Circuit Behavior
15/22
15
Source voltage and the voltage applied
to each load is the same
Load Resistance determines currentthough each load
Total circuit resistance less than lowestload resistance
wwww
w w w w
4
2
R1 R212
volts
3 amps 6 amps
Parallel Circuits
Total circuit current equals
the sum of the branchcurrents
It = the sum of the individual branches3+6=9 amps
16
8/14/2019 Electrical Circuit Behavior
16/22
16
Parallel Circuit Review
Ohms Law can be applied to a series circuit to find unknownvalues as long as you have at least two of values required towork the formula and, you remember the following rules for
a parallel circuit.1. The source voltage and the voltage applied to a load (resistance) is
exactly the same and cannot vary.
2. The current through each load is determined by the resistance value ofeach resistor.
3. The resistance total of the circuit will always be less than the lowestresistors value.
4. The total current flow in the circuit will be equal to the sum of the
branch currents through each resistor.The total current in the circuitis divided between the loads, therefore, a parallel circuit is sometimesreferred to as a Current Dividing Circuit.
17
8/14/2019 Electrical Circuit Behavior
17/22
17
Series Parallel Circuits
Series Parallel Circuit
As the name implies, the series-parallel isa combination of of both types of circuits.
One or more of the loads is in series, whilethe others are in parallel.
18
8/14/2019 Electrical Circuit Behavior
18/22
18
Series Parallel Circuits
ww
ww
ww
ww12
volts
WWWW
Dimmer
Series-Parallel Circuit Rules
1. The Resistance Total of the circuit isequal to the sum of the parallel resistanceplus the series resistance.
2. The Current in the series portion of thecircuit is equal to the sum of the branchcurrents.
3. The VoltageDrop across the series
resistance will reduce the voltage suppliedto the parallel branches.
12 volts 6 volts 6 volts
19
8/14/2019 Electrical Circuit Behavior
19/22
19
= ------------
= ---------------
= ---------
(R X R ) 2 3
(6 X 3 )
Rtp
Rtp
R
tp
Rtp
(R + R ) 2 3
18 Ohms
9 Ohms
= 2 Ohms
Circuit Total Rt 4 Ohms
Series Parallel Circuits
(6 +3 )
Rtp=
+ Rts
Rt =+2 2 =
4
ww
ww
ww
ww
12
volts
WWWW
Dimmer
Series Resistance
R1Set at
2 Ohms
Parallel
ResistanceR 2 6
Parallel
ResistanceR 3 3
The Resistance Total of the circuitis equal to the sum of the parallelresistance plus the series resistance.
20
8/14/2019 Electrical Circuit Behavior
20/22
20
Current in the the series portion ofthe circuit is equal to the sum of
the branch currents.
Series Parallel Circuits
ww
ww
ww
ww
12volts
WWWW
Dimmer
Series Resistance
R1Set at
2 Ohms
Parallel
ResistanceR 2 6
Parallel
ResistanceR 3 3 It
It
=
=
=
-----
------
Rt
12Volts
4 Ohms
3 Amps
Sv
It
21
8/14/2019 Electrical Circuit Behavior
21/22
21
6 Volts
3 Amps
Series Parallel Circuits
=
=
=
R ItX
X2 Ohms
6 Volts
Vdr
Vdr
Vdr
wwww
wwww
12volts
WWWW
Dimmer
Series Resistance
R1Set at
2 Ohms
ParallelResistance
R 2 6ParallelResistance
R 3 3
The Voltage Drop across the seriesresistance will reduce the voltagesupplied to the parallel branches
Voltage Drop
6 volts 6 volts
22
8/14/2019 Electrical Circuit Behavior
22/22
22
Series Parallel Circuits Review
Ohms Law can be applied to a series-parallel circuit to find
unknown values as long as you have at least two of valuesrequired to work the formula and, you remember the followingrules for a parallel circuit.
1. The Resistance Total of the circuit is equal to the sum of the parallelresistance plus the series resistance.
2. The current in the series portion of the circuit is equal to the sumof the branch currents.
3. The Voltage Drop across the series resistance will reduce the voltage
supplied to the parallel branches.