Name:
Reading 3.7
Date:
Electrical Circuit
A circuit is a complete path around which electricity can flow. A circuit must include a source
of electricity, such as a battery. Materials that allow electric current to pass through them easily
(conductors) can be used to link the positive and negative ends of a battery, creating a circuit.
The wires have to go from the power source to the device and back again, so that the electrons
can go out and come back. Many circuits have a switch so that they can be turned on and off.
When the switch is off, or “open”, it makes a gap in the circuit and the electrons are not able to
flow around. When the switch is turned on, or “closed”, it closes the gap and the electricity is able to
move an make the device work.
Let’s think about a practical device – like a laptop. A laptop needs to be charged in order to
work. When the charger is not plugged into the computer, the computer is not being charged. The
power cord represents an open circuit because the electrons are not able to flow from the
power source to the computer. When the charger cord is plugged into the power source and the
computer, this represents a closed circuit because the electrons are now able to flow from the
power source to the computer. Now the computer can be charged.
Simple Circuit
Circuit Symbols
wire
battery
lightbulb
© TeachinginaWonderland 2016
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Simple Circuit
lightbulb
battery
wire
What is a simple circuit?
In a simple circuit, there
are 3 – 4 items needed.
You need a source of
electrical voltage. You
need a conductive path
that allows for the
movement of charges.
You also need a load that
uses electricity to do
work.
Open Circuit
open
switch
lightbulb
battery
What is an open circuit?
In an open circuit, there
is a gap in the circuit and
the electrons are not
able to flow around. With
the open circuit, the
switch (if you are using
one) is left open or up.
wire
Closed Circuit
closed
switch
lightbulb
battery
wire
© TeachinginaWonderland 2016
What is a closed circuit?
In a closed circuit, there
is not a gap in the circuit
and the electrons are
able to flow around. With
the open circuit, the
switch (if you are using
one) is left closed or
down touching the metal
prongs.
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