Series Circuits
In this presentation you will:
 explore the design and construction of electric
circuits connected in series combinations
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Sunday, March 17, 13
Electric Current
Electric current is the movement
of electric charge around a circuit.
Current will only flow if:
 there is a power source,
such as a cell or battery
(more than one cell)
 there are no gaps in the circuit
(such as an open switch)
-
+
For current to be useful, a circuit needs to contain at
least one component, for example, a lamp or buzzer.
Current does not get used up. The current that goes
into a cell is equal to the current that comes out.
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Sunday, March 17, 13
Electric Circuits
This circuit has a cell,
a lamp, and
connecting wires. A
switch is used to
complete the circuit.
+
-
-
+
We usually use circuit
symbols in circuit
diagrams, instead of
photographs and pictures.
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Sunday, March 17, 13
Question 1
In which of the following circuits would current flow?
A)
C)
B)
D)
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+
-
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Sunday, March 17, 13
Question 1
In which of the following circuits would current flow?
A)
C)
B)
D)
-
+
-
+
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Sunday, March 17, 13
Electromotive Force
Current is pushed
around a circuit by a
power source.
EMF
-
+
The force that pushes
the current is called the
electromotive force
(emf).
The emf provides energy to the carriers of the
electric charge in the circuit. It is measured in
volts (V).
Sunday, March 17, 13
Next >
Circuit Symbols
Here are some of the symbols we use. Wires are
always shown as straight lines.
-
+
-
+
Cell
_
+
Battery
Lamp
OR
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Sunday, March 17, 13
Circuit Symbols
Other circuit symbols include:
Switch (open)
ON
OFF
Switch (closed)
ON
OFF
Ammeter
A
Voltmeter
V
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Sunday, March 17, 13
Circuit Diagrams
The symbols can be put together to make circuit
diagrams.
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Sunday, March 17, 13
Question 2
Which of the following shows a circuit containing
two lamps, a cell, a switch, and an ammeter?
A)
-
+
C)
B)
+
V
A
A
-
-
+
A
D)
-
+
A
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Sunday, March 17, 13
Question 2
Which of the following shows a circuit containing
two lamps, a cell, a switch, and an ammeter?
A)
-
+
C)
B)
+
V
A
A
-
-
+
A
D)
-
+
A
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Sunday, March 17, 13
Circuit Diagrams
-
This series circuit
can be arranged
in several
different ways.
+
+
Arrangement 1
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+
+
All arrangements
are valid.
Arrangement 2
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+
+
-
Arrangement 3
Sunday, March 17, 13
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Question 3
The top image shows a circuit. The circuit diagram
has been drawn below it. What is wrong with the
way the circuit diagram has been drawn?
+
A) The circuit diagram does
not show the lamp.
B) The circuit diagram has a
break in it.
C) The lamp is in the wrong
place in the circuit diagram.
D) The circuit diagram does not
show the power source.
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Sunday, March 17, 13
Question 3
The top image shows a circuit. The circuit diagram
has been drawn below it. What is wrong with the
way the circuit diagram has been drawn?
+
A) The circuit diagram does
not show the lamp.
B) The circuit diagram has a
break in it.
C) The lamp is in the wrong
place in the circuit diagram.
D) The circuit diagram does not
show the power source.
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Sunday, March 17, 13
Circuits
Circuits can be constructed
in two ways:
_
+
 in series
 in parallel
In a series circuit, the same
current flows through each
part of the circuit.
_
+
A parallel circuit has branches.
The current is divided between
the different routes.
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Sunday, March 17, 13
Circuits
This simple circuit has one
power source (a cell), one
component (a lamp), and
connecting wires.
Electron current flows from
the negative terminal of the
cell, through the lamp, to the
positive terminal of the cell.
Cell
_ + _
+
Lamp
As more cells are added in series, more current
flows and the lamp glows more brightly.
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Sunday, March 17, 13
A Series Circuit
This circuit has one cell,
two lamps, and
connecting wires.
Cell
_ +
There is only one path
for the current to take.
The current flows
through both lamps,
one after the other.
This is a series circuit.
Sunday, March 17, 13
Lamps
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Breaks in Series Circuits
You have seen that
the same current
flows through each
component of a
series circuit.
_
+
_
+
If one of the lamps
failed, the circuit would
be broken as the current
could no longer flow.
In this circuit, all the lamps would go out.
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Sunday, March 17, 13
Summary
In this presentation you have seen:
 the concept of electric current and electromotive
force
 circuit symbols and diagrams
 circuits connected in series combinations
End >
Sunday, March 17, 13