ELECTRICITY IES RĂo Cabe
1) ELECTRICITY AND MATTER. 1.1. Conductor and insulators Covadonga Yugueros 1.2. How to obtain electricity Valbuena 1.3. The transport of electric energy 1.4. Effects of electric current 2)Electric quantities 2,1. Electric current 2.2. Voltage 2.3. Resistance. 3) Ohm's law 4)Electric circuits 4.1. Components of an electric circuit 4.2. Representation and symbols. 5)Types of circuits. 5.1. Series circuits 5.2. Parallel circuits 5.3. Seriesparallel combination circuits
5. Types of circuits There are lots of different ways to connect components in a circuit
The most common connections:
Series circuits
Parallel circuits
5,1. Series circuits

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Components are placed one after the other in the circuit. There is only one possible path for the electric current to flow through
Series circuits The same current flows through all the components
The total resistance is the sum of all the resistances R1
R2
R3
Rtotal = R1 + R2 + R3
The voltage of the battery is the sum of the voltages of all the receptors in the circuit.: B1
B2
V2
V1
V total +
B3
V3
Vtotal = V1 + V2 + V3
Series circuits If one of the components stops working, none of them will work because the circuit will be open.
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9V
9V
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9V
Batteries en series: If we connect some batteries in serie, the total voltage is the sum of the voltage in each battery +
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+
3V
1,5V
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1,5V
1,5V
4,5V
+
1,5V
1,5V
Batteries in series: The negative pole of one battery with the positive pole of the next one.
Series circuits Fuses and control elements are always connected in series with the receptors that must be protected or controlled.
Control element +
Fuse

Practice Series Circuit
Practice2 Series Circuit
Example of a series circuit:
In the following circuit calculate: * The total resistance
R1
R2
50 立
100 立
30 立
* Total current * Voltage on each receptor.
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9V
a
b
c
Rtotal = R1 + R2 + R3 Ohm's law
Itotal = VTotal /RTotal
In a series circuit the current is the same in all elements.
Ohm's law in each component
V1 = R1 * I V2 = R2 * I
5,2. Parallel circuit The components are connected on different branches of the wire. There are several possible paths for the electric current to flow through
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Dia g
Parallel circuit
The intensity is shared by all the possible paths The current will be higher
As lower be the resistance Itotal
I2
Total current is the sum of the intensity in each branch
I1 +
Itotal
10 立
5立
I1
I2
Itotal = I1 + I2 Itotal = I1 + I2 + I3
Parallel circuits
Voltage is the same in Vtotal
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each branch
V1
V2
Vtotal = V1 = V2 We can calculate the total resistance using this formula R1
100 立
1
Rtot
=
1 1 R1 + R2
1 1 1 1 Rtotal = R1 + R2 + R3 1
Rtot
R2
100 立
1
Rtot +
9V
=
1 50
Rtot = 50立
=
1 100
+
1 100
=
2 100
Parallel circuits If one of the components in parallel stops working, the rest continue to work because the electric current takes another path.
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+
+ 9V
9V
9V
Batteries en parallel: Poles of the same sign are joined together. These batteries must have the same voltage, and the circuit is equivalent to having another battery of the same voltage but longer. 1,5V
1,5 V
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1,5V
Parallel circuits If a wire is in parallel with a receptor, this will not work, because the current will choose the path that less work required.
This is a short circuit +
Lamp is in a short circuit
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Practice 1 Parallel Circuit Practice 2 Parallel Circuit
Example of a parallel circuit:
In the folllowing circuit claculate:
12 立
6V
* Total resistance
M
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* Total current * Voltage and current in each component.
a
b
c
1 1 1 1 Rtotal = R1 + R2 + R3 Ohm's law
Itotal = VTotal /RTotal
In a parallel circuit the voltage is the same for all elements.
Ohm's law in each component
I1 = V/R1 I2 = V/R2
6立
5,3. Seriesparallel combination circuits These circuits contain devices connected in series and in parallel
B1
B2
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B3
Di ag
ra m B1
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B3
B2
Seriesparallel combination circuits In the following circuit analyze what elements are in series and which are in parallel. B1 is in series with the parallel of B2  B3
B2 y B3 are in parallel
B1
+
B2
B3
9V
B2
B1
M
B1 y B2 are in series
Motor is in parallel with B1  B2
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