Transcript Electricity – Simple Circuits

KS4 Electricity – Simple Circuits
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Circuit symbols
Instead of drawing intricate diagrams of
electrical components we use circuit
symbols to simplify how circuits are set up.
You will need to learn these, how to
draw them, and how to identify them.
Filament
lamp
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Use a textbook or other resource to fill in
the table below:
Component
Circuit symbol
Fuse
Resistor
Motor
M
Switch
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Use a textbook or other resource to fill in
the table below:
Component
Circuit symbol
Cell
Battery
Ammeter
A
Voltmeter
V
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Breaks in circuits
Set up the circuit shown….
…does the bulb light?
NO
Why does the bulb not light?
There is a break in the circuit.
For electricity to flow in a circuit it must be able to flow from
one terminal of the cell or battery to the other terminal.
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Letting electricity pass
Do all materials let electricity pass?
Which materials will and which materials will not?
Set up the circuit shown and place different materials in
the gap in the circuit. Record which materials let
electricity through (the bulb lights if electricity flows).
What do we call a material that lets electricity flow through it? CONDUCTOR
What do we call a material that does not let electricity flow
through it?
INSULATOR
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Which of these bulbs will light?
Build the circuits!
Electricity will always
take the easiest path.
A.

B.
C.
x
x
It is easier to flow through
a wire than through the
bulb.
So in circuits B and C the
electricity does not pass
through the bulb.
The cell or battery still
loses energy because ,
electricity is still flowing.
This type of circuit is
known as a SHORT
CIRCUIT.
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Electron flow
Electricity in wires is a flow of electrons along the wire.
What do we call this flow of electrons? Electrical current
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Current Flow
When we talk about current flowing we say that
current flows out of the positive terminal of the cell
and back into the negative terminal.
Conventional Current
What do we call this flow?
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Electron Flow
However, the electrons flow from the negative side of
the battery to the positive side. These are the particles
which are actually moving through the conductor.
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Conventional current and Electron flow
Whenwill
What
charge
do
electrons
two
a positive
negative
do were
electrons
and
discovered,
charges
a negative
have?
do physicists worked out
what
if
charge
placed
was
donear
really
to each
tohappening.
each
other?
other? Negative
They will attract
repel each
eachother.
other.
Negatively charged electrons are repelled out of the
negative terminal of the cell. They then travel round the
circuit and are attracted back to the positive terminal.
Conventional
current
electrons
Conventional
current
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Current
In an electric c____,
ircuit current is the flow of
e_______.
ore
lectrons The bigger the current, the m___
electrons are flowing around the circuit. The
w___
ires carry the electrons from one terminal
erminal
around the circuit to the other t______.
lamps
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Set up the two circuits shown:
A.
BRIGHTER
B.
DIMMER
What
do
happens
The
Series
we
Parallel
In circuit
call
other
ifare
Circuit
circuit
you
Circuit
circuit
Athe
bulb
the
unscrew
B?
A?
bulbs
staysthe
goes
out.
lit.
are
a
one
bulb
the
bulb
inbrightest.
circuit
in Circuit
B? A?
In
which
circuit
bulbs
brightest?
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Measuring current I
In a series circuit the current is the same
Set
up
theyou
circuit
shown
below……
…and
The
What
current
then
do
record
isnotice
the
the
same
about
current
for
the
each
using
readings?
ammeter.
an ammeter
wherever
you
measure
it.
in the places shown below.
When measuring current ammeters are always
placed in series.
A
A
A
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Measuring current II
For a parallel circuit, the current that leaves the cell or battery is the same
as
the
that
returns
to at
the
cellreadings?
or battery.shown.
The current does not get
…then
What
record
you
the
notice
current
about
the
the
locations
Setcurrent
updo
the
circuit
shown
below……
used up by a circuit, just the energy the electrons are carrying.
A1 = A4
A1
Ammeter
Current
(A)
A1
A2
A3
A4
0.8
0.4
0.4
A4
A2
A3
The sum of the currents in the branches of a
parallel circuit is the equal to the current that
leaves the cell or battery.
A1 = A2 + A3 =A4
0.8
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Voltage
oltage is a measure of how big a push
The v_____
lectrons are given as they leave the
the e_______
attery The bigger the voltage, the
cell or b_____.
ush
bigger the p___.
ower s_____
upply produces
The cell, battery or p____
the voltage.
lamps
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Measuring voltage I
For a series circuit, the sum of the voltages for each component
is equal
todo
theyou
voltage
across
the
orlocations
battery. shown.
Set
up
the
apparatus
as shown……
…then
What
record
notice
the voltages
about
the
atcell
the
readings?
V1 = V2 + V3
V1
NB Voltmeters are
connected in parallel
V2
Voltmeter
Voltage
(V)
V1
V2
V3
1.5
0.75
0.75
V3
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Series circuit
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Measuring voltage II
V1
For
..measure
parallel
circuit,
voltage
theat
Setado
up
thethe
apparatus
What
you
notice
about
the
voltage
locations
across
shown.
the
as
shown….
your
readings?
cell/battery is the same
as the voltage across
each branch.
V1 = V2 = V3
V2
V3
Voltmeter
Voltage
(V)
V1
V2
V3
1.5
1.5
1.5
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Parallel circuits
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Name this circuit symbol.
V
A. Ammeter
B. Switch
C. Bulb
D. Voltmeter

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What component is used to measure
electrical current?
A. Switch
B. Resistor
C. Ammeter

D. Voltmeter
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Which component changes electrical
energy into light energy?
A. Bulb

B. Switch
C. Cell
D. Battery
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Which component is a store of chemical energy?
A. Bulb
B. Battery

C. Switch
D. Resistor
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Which of these materials is not a conductor
of electricity?
A. Water
B. Graphite
C. Lead
D. Wood

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