KNOW YOUR COMPONENTS
COMPONENT
CELL
BATTERY
SYMBOL
ILLUSTRATION
DESCRIPTION
A device that changes chemical energy into
electricity.
A collection of cells placed together.
WIRE
Wires connect the components together to
make a circuit.
BUZZER
This makes a buzzing noise when electricity
flows through it, the higher the voltage the
louder the buzz.
MOTOR
A device that converts electrical energy into
mechanical energy.
SWITCH
(ON)
This will turn your circuit on. It makes a circuit
when flicked on by allowing electricity to flow
through it.
SWITCH
(OFF)
This will turn your circuit off. It breaks the flow
of electricity through the circuit when flicked
off.
LDR
This is a light sensor. The more light it detects,
the more voltage it allows through.
LIGHT DEPENDENT RESISTOR
LED
LIGHT EMITTING DIODE
This is a tiny light that uses very little electricity. It
has one leg longer than the other which means that it
must be connected to the positive side of the circuit.
POTENTIOMETER
A Potentiometer is a resistor that you can control!
Turning the knob on the potentiometer increases
and decreases the amount of resistance a bit like a
tap and the flow of water.
RESISTOR
These limit the flow of electricity through a
circuit. Some limit the flow more than others.
CAPACITOR
A capacitor is like a big bucket, it stores up charge,
waits until its full and then releases it all in one go.
How much charge depends on the size of the
capacitor, which is measured in Farads after
physicist Michael Faraday.
SPEAKER
A device that converts electrical energy into
vibrations. (sound)
DIODE
A Diode is a component that allows current to
flow in just one direction. It must go into your
circuit the correct way round, the white band
indicates the negative side of the diode.
555
TIMER
This is a 555 timer also known as an Integrated
Circuit (IC). This is a whole circuit in itself, but
very very small and made of silicon. These are the
brains of the circuit.
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KNOW YOUR CIRCUITS
ELECTRIC CHARGE
ELECTRIC CURRENT
Have you ever heard a crackle when taking off a
jumper? This is caused by tiny electric charges
made by your clothes rubbing together.
It's called static electricity.
When electric charges move in a wire, we say
that an electric current flows in the wire. It's like
the way a current of water flows in a river.
For an electric current to flow, we need two things:
When ice particles in storm clouds bump
together, they become charged with electricity
which is eventually released as lightning.
1. Something to make the electricity flow, such
as a battery.
A cell turns chemical energy into an electrical
charge that we use in electrical devices.
2. A complete path for the current to flow this is
called an electric circuit.
ELECTRIC CIRCUITS
The simplest complete circuit is a piece of wire from
one end of a battery to the other. The electric current
can flow but nothing useful happens. The wire just
gets hot and the battery goes flat.
To do something useful with the electric current, we
need to put an electrical component into the circuit,
such as a lamp or motor.
The bulb will only light if there is a battery and a
complete circuit.
INCOMPLETE
CIRCUIT
NO
BATTERY
COMPLETE
CIRCUIT
SERIES CIRCUITS
A series circuit has several components
one after the other in a row.
If you follow the circuit diagram from
one side of the cell to the other, you
should pass through all the different
components, one after the other,
without any branches.
In a series circuit, if a lamp breaks or a component is disconnected, the
circuit is broken and all the components stop working.
If you add more lights into a series
circuit, the lights will be dimmer.
Series circuits are useful if you want a warning that one of the components
in the circuit has failed. They also use less wiring than parallel circuits.
PARALLEL CIRCUITS
A parallel circuits has different
components connected on different
branches of wire.
If you follow the circuit diagram from one
side of the cell to the other, to pass through
all the different components you must
follow all the branches.
If you add more lights into a parallel circuit,
the lights remain bright, as the current is
shared between components.
In a parallel circuit,
if a lamp breaks or
a component is
disconnected from
one parallel wire,
the components on
different branches
keep working.
Parallel circuits are
useful if you want
everything to work,
even if one
component fails.
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