Download Simple Electrical Circuit - E

GRADE 7
Name:
Definitions: Electricity is the flow of electrical energy or charge. These charges move
from one place to another in an electric circuit, carrying electrical energy. A circuit
is the actual pathway the electricity flows along, from a power source, to where it is
needed and back to the power source.
A simple circuit consists of these components:
• An energy source (cell or battery)
• A light bulb (or item which changes the electrical energy into another form of
energy for a certain purpose)
• Connectors (wires)
• A switch
All of these components must be connected for energy to flow through the circuit.
If the switch is open (off ) the circuit is open and electricity will not flow through
it. If the switch is closed (on), the circuit is closed and complete and all of the
components are connected, so electricity can flow.
CELLS
CONNECTORS
LIGHT BULBS
SWITCHES
Source of electrical
energy.
Have a number on
them which tell
us their voltage.
Voltage tells us
about the cells
ability to “push”
energy through
the circuit.
Have positive and
negative poles.
Connect all of
the components
together and allow
energy to flow
through the circuit.
Conduct electricity.
It is safest if
these wires are
insulated (coated)
with plastic. This
prevents shocking
and short circuits.
Indicate whether
or not electricity
is flowing through
the circuit.
Also have a
voltage reading.
Voltage in the
circuit (from the
cell) must not
exceed the bulb’s
voltage or it will
burn out.
Open or close the
circuit.
Many different
types including
push/press switches, and those that
toggle as well
as home-made
switches.
A switch is any
point in the circuit
which you use to
connect or break
the circuit.
© e-classroom 2014 www.e-classroom.co.za
Grade 7 Term 3 Technology: Electrical Systems and Control; Simple Electrical Circuit
Simple Electrical Circuit
GRADE 7
Each component is represented in circuit diagrams using a universal symbol. We use
these symbols because the real-life objects may differ. For example, picture a light
bulb in your mind and draw a picture of it. Now ask a friend to do the same. You will
note that these two drawings will look quite different.
Here are the symbols we use to represent the components of an electric circuit:
Component
Picture
Symbol
Cell Battery(2 or more cells
connected)
(Long line = positive
Short line = negative)
Connectors
Switch (open)
Switch (close)
Light bulb
ACTIVITY: Complewte in your class workbook
1)
Build a simple electric circuit using the following components:
2 x AA cells (1,5V); a 2xAA cell holder; a light bulb; a switch and connectors.
2)
Draw a circuit diagram to represent your simple circuit.
3)
Explain what happens when the switch is closed.
4)
Explain what happens when the switch is open.
© e-classroom 2014 www.e-classroom.co.za
Grade 7 Term 3 Technology: Electrical Systems and Control; Simple Electrical Circuit
Circuit diagrams
GRADE 7
Activity:
1) Build a simple electric circuit using the following components:
2 x AA cells (1,5V); a 2xAA cell holder; a light bulb; a switch and connectors
2) Draw a circuit diagram to represent your simple circuit.
Drawing must include two cells, a light bulb and a switch (which can be drawn open
or closed). The arrow is important as it shows the flow of current, which is always
from the positive pole, through the circuit and back to the negative pole.
3) Explain what happens when the switch is closed.
When the switch is closed, the circuit is complete or connected. Energy can flow from the cells through the circuit. The light bulb lights up because there is a flow of electricity.
4) Explain what happens when the switch is open.
When the switch is open, the circuit is incomplete or disconnected. Energy cannot flow from the cells through the circuit. The light bulb does not light up because there is no flow of electricity.
© e-classroom 2014 www.e-classroom.co.za
Grade 7 Term 3 Technology: Electrical Systems and Control; Simple Electrical Circuit
Answer sheet