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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
BOOK 1
MODERN
LIVING
& ENERGY
SECTION 3
BUILDING ELECTRICAL CIRCUITS
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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
SYMBOLS
It is important to know the symbols of components in electrical circuits.
Switch
Lamp
Diode
Cell
Resistor
Fuse
A
Battery
V
Voltmeter
1
Ammeter
MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
ACTIVITY
Look at the following circuit diagrams and identify the components.
A
V
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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
3
MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
CIRCUITS
There are two types of electrical circuit: series circuits and parallel circuits. In a series
circuit all of the components follow the same path. In a parallel circuit there are branches
where the components sit.
SERIES CIRCUIT
All of the components follow the same path. Also, the current is the same throughout the
circuit and the voltage across each component adds up to the voltage of the power supply.
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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
PARALLEL CIRCUIT
In a parallel circuit the components are in branches. Here the voltage across all
components is the same and the current within each branch is equal to the current of the
power supply.
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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
ADVANTAGES, DISADVANTAGES AND EXAMPLES
Circuit type
Advantages
Disadvantages
Example
Series
Very easy and
simple to setup.
Lamps cannot
be controlled
individually.
Fluorescent lights.
You can add more
power to increase
the output. E.g.
more power brighter lamps.
A flash light.
The more output
(lamps) in a circuit
the dimmer the
lamps.
If a single lamp
goes out, the
entire circuit stops
working.
Parallel
If one component
breaks it does not
affect the rest of
the circuit.
More lamps can be
added to a parallel
circuit without any
of them getting
dimmer.
Harder to setup
than a series
circuit.
Adding more power
does not increase
the output e.g. if
a 5 volt battery
which can power a
light for two hours
is added to an
identical battery,
the output is still 5
volts but the lamp
will now stay on for
four hours.
6
Ring main in a house.
MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
MEASURING CURRENT AND VOLTAGE
Voltage in a circuit is measured using a voltmeter. To measure the voltage across an
electrical component the voltmeter must be added into the circuit in parallel to the
component you want to measure.
V
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MODERN LIVING AND ENERGY - SECTION 3
BUILDING ELECTRICAL CIRCUITS
The current in a circuit is measured using an ammeter. To measure the current in a circuit
the ammeter needs to be added in series.
A
ACTIVITY
Build the first three circuits from the activity on page 3. Measure and record the
voltage across each component and current within each circuit.
Circuit
Voltage
Current
1
2
3
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