The word circuit literally means a route that
starts and finishes at the same place. An
electrical circuit has a source of power (the
battery), the connecting wires (the conductors),
and the device that is collecting the electrical
power (the load). For the load to receive the
electricity the circuit must be continuous. If
the circuit is broken the power cannot get
through to power the load.
Circuits
light
bulb
“load”
closed switch
conductors
Controlling the Electrical Current:
In an electrical circuit, there needs to be a way
to control when the power will flow through it
and when it won’t. That is the job of the switch.
A switch can be open or closed. A closed switch
keeps the flow of electricity flowing through the
circuit to power a device. An open switch creates
a gap in the circuit, so electricity stops flowing to
the device. It “breaks” the circuit. A switch can
also be used to change the pathway of electricity
in a parallel circuit to power a different devise.
Another way electrical current has been
controlled is through fuses. A fuse will literally
melt down if too much current is forced through
it, creating a circuit gap – which stops he flow of
electricity. This was meant to stop electrical fires,
but requires replacing the burned out fuse with a
new one each time to get the current going again.
battery
light
bulb
“load”
open
switch
conductors
battery
A newer current protection device is the breaker. A breaker or circuit breaker is a switch that is designed to
activate and break the flow of electricity when too much current is flowing through the system to prevent an
electrical fire. It can be reset by hand, so does not have to be replaced each time like a fuse.
Instead of simply stopping the flow of electricity, it is sometimes necessary to just decrease how much current
a device is getting. This is done by resistor. A resistor can lower the current that is flowing into more fragile
devices like a computer circuit board.
©Sheri Amsel
www.exploringnature.org
Circuits – Vocabulary Assessment Quiz
The word circuit literally means a route that starts and finishes at the same place. An electrical circuit has a
source of power – the ______________________________________, the connecting wires – the
____________________________________________________________, and the device that is collecting the
electrical power – the ________________________________________. For the device to receive the electricity
the circuit must be continuous. If the circuit is broken the power cannot get through to power the load.
In an electrical circuit, there needs to be a way to control when the power will flow through it and when it won’t.
That is the job of the switch. A switch can be open or closed. A _________________________ switch keeps the
flow of electricity flowing through the circuit to power a device. An ___________________________ switch
creates a gap in the circuit, so electricity stops flowing to the device. It “breaks” the circuit. A switch can also be
used to change the pathway of electricity in a parallel circuit to power a different device.
Instead of simply stopping the flow of electricity, it is sometimes necessary to just decrease how much current a
device is getting. This is done by a _______________________________________________ that can lower the
current that is flowing into more fragile devices like a computer circuit board.
There are three kinds of electrical circuits. A ____________________________________ circuit has a just one
device that gets its electricity from the power source and sends it along the conductors in the circuit to touch
the power source’s opposite end (terminal). A _______________________________________ circuit has more
than one device (component loads) that are joined end-to-end by connecting wire (conducting wire). If there is
a break anywhere in the wire (conductor), all the devices will lose power, because the circuit has been broken.
A ____________________________________________________ circuit has branching paths to each device
(component loads) that is getting electricity. If the wire (conductor) to one device (component load) is broken in
a parallel circuit, the other devices will still get power. This makes a better circuit for wiring a house.
©Sheri Amsel
www.exploringnature.org