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Electricity
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Menu
• Household Plugs & Fuses
• Power & Fuses
• Static Electricity
• Charge
• Dangers of Static
• The Cost of Electricity
• Uses of Static
• Magnetism
• Circuit Symbols
• Electromagnets & Devices
• Current
• Generating electricity
• Voltage
• Electric Motors
• Resistance
• Transformers
• Summary Table
• Power Stations
• Electrolysis
• National Grid
• AC & DC
• Related Websites
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Static Electricity
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Static Electricity
Static electricity is about
charges that are NOT free to
move. This causes them to build
up in one place and it often
results in a spark or shock when
they finally move
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How Can Materials Become
Charged?
When two insulating materials are
rubbed together, electrons can be
‘scraped off’ from one material to
another.
This results in a positive static charge
on one and an equal but opposite
negative static charge on the other
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Which Way Are the
Electrons Transferred?
This depends on the materials involved
Negatively charged rod
Positively charged cloth
+++++
+++++
+++++
The electrons have moved
from the cloth to the rod
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Only Electrons Move
A positive static charge is always
caused by electrons moving
elsewhere
Just think about
it…the electrons are
on the outside of the
atom…. the protons
are held in the centre
Protons
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Electrons
Like Charges Repel and
Opposite Charges Attract.
- ----
------
The balloons both have the same
static charge and will repel each
other
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The Van de Graaff Generator can
make your hair stand on end!
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Each hair has
the SAME
charge and
therefore
repels the
others
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Attraction
The comb has been
charged by friction
and has gained
electrons (it has a
negative charge)
It induces a separation of charges on
the paper and attracts the pieces
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Explain what is happening
here….
- -- --- - - -- - -- --
Has the balloon ‘gained’ or ‘lost’
electrons?
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Explain What You Think Is
Happening
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Why is the water ‘bending’?
Charged
comb
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The Van de Graaff
Generator
As electrons are rubbed
off the belt they collect
on the domes.
If a big enough charge is
built up then the voltage
becomes high enough to
ionise the air molecules
and the electrons ‘jump’ to
Earth as a spark
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Can you see the
mad scientist?
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Dangers of Static
Electricity
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Dangers of Static
As the fuel moves through the pipe it gains
electrons from the pipe, making the fuel
negative and the pipe positive. This can
result in a spark and ultimately an explosion
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The helicopter can become
charged by the friction of the
rotor blades against the air
For safety
reasons, the
rescuer has a
conductor
attached below
him to discharge
the current safely
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How Can We Refuel Safely?
Refuelling can be carried out
safely if either the fuel tank
is earthed with a copper rod
or the tanker is connected to
the plane by a copper
conductor
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How Do We Get Thunder &
Lightning?
Particles inside a thunder cloud move
around and get charged by friction.
The heavier particles accumulate at the
bottom of the cloud gaining a negative
charge. These are attracted to the earth
and we get a BIG SPARK!
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Lightning – Did you Know?
A bolt of lightning travels at
120 kilometres per second. One
bolt has enough energy to run
the whole of the UK for a week
It can heat the air around it to
28,000 0C (Several times
hotter than the surface of the
sun)
About a hundred lightning
bolts hit the Earth every
second
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Uses of Static
Electricity
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Can We ‘Use’ Static Electricity?
We use static
electricity in dusters
and floor wipes to
attract the dust
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Electrostatic Paint Spraying
The paint is given a
positive charge making
each drop repel as they
are ‘like’ charges.
The car being sprayed is
given a negative charge
(or connected to earth),
so the droplets are
attracted to it
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+ +
+ +
+ +
- -- -- - --
The Advantages of
Electrostatic Paint Spraying
Are:
• Less paint is wasted
• A more even coat of
paint is achieved
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How does a Photocopier use
Static Electricity to print
documents?
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1) Inside the photocopier
A light sensitive drum is given a
negative charge
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2) An image of the document
is projected onto the plate
The bright areas lose their charge
but the dark areas keep it
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3. Powdered ink (called toner) is
attracted to the charged areas
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4) A blank sheet of paper is
pressed against the paper
and picks up the ink
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5) The paper is heated so
that the powdered ink melts
and sticks to the paper
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Circuit Symbols
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Identify the Circuit
Symbols
A Filament
lamp/ Bulb
A Cell
A Battery
of 2 Cells
A Switch
A Battery
of a number
of cells
A fixed
Resistor
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Identify the Symbols
Variable
Resistor
L.D.R
Thermistor
Fuse
Heater
Loudspeaker
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Identify the Circuit Symbols
A
V
M
Ammeter
L.E.D
Voltmeter
Motor
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Draw the Circuit Symbols
Component
Circuit Symbol
Thermistor
L.D.R
Fuse
L.E.D
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Current
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Electrons Flow in the Opposite
way to the Conventional Current
-+
Electrons are
negatively
charged and
therefore flow
from negative
to positive
e-
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We
normally
say that
the
current
flows
from
positive
to
negative
Current
Current is the FLOW
OF ELECTRONS
AROUND A CIRCUIT
In metals, current is
carried by electrons
The unit of
current is the
ampere (A)
We use an
ammeter to
measure current
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Ampere
This is the
scientist AMPERE.
He studied current
in circuits and gave
his name to the
unit of current
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Current in a Series Circuit
2A
2A
2A
The Current in a Series Circuit
is the Same at Every Point
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In a series circuit the bulbs
are all the same brightness
If the
bulbs are
of the
same
rating!
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Current Questions
A
B
C
1) The current reading for bulb B is 2A. What
are the readings for bulbs A and C?
2) Bulb suddenly fails. What happens to bulbs
A and C?
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What Is the Current at This
Point?
6A
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Brightness of Bulbs in a
Series Circuit
If a cell is added
the current will
increase and the
bulb gets brighter
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Brightness of Bulbs in a
Series Circuit
If a bulb is added the
current will decrease as
there is greater
resistance in the circuit
and the bulbs get dimmer
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Current in a Parallel Circuit
A PARALLEL circuit has more than one path
for the current to flow through
Bulb A
Bulb B
Assuming both bulbs
are the Same…they
will be the same
brightness
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Current in a Parallel
Circuit
The Advantages of a
parallel circuit are:
Bulb A
Bulb B
• If one bulb fails
….the other will remain
on
• Both bulbs can be
switched on separately
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Current in a Parallel Circuit
6A
6A
2A
2A
2A
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The total
flow of
current is
equal to the
total
current
from all of
the
branches
What is the ammeter reading?
9A
3A
3A
3A
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Voltage (Potential
Difference)
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Voltage Is the Driving Force That
Pushes the Current Around the
Circuit
We need Energy to
push the electrons
around the circuit.
In this case the
energy comes from
the lemon (in the form
of chemical energy)
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Potential Difference/ Voltage
This is VOLTA. He
studied the driving
force that pushes
current around a
circuit. He gave his
name to the unit of
Potential Difference
The unit of Potential Difference is
the VOLT (V)
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Voltage in a Series Circuit
12V
4V
4V
4V
12V
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The voltage in a
series circuit is
shared across
each
component. The
sum of the
voltages across
each component
equals the
source voltage
What Is the Voltage?
?V
8V
8V
8V
?V
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6V
6V
6V
Voltage in a
Parallel
Circuit
The voltage is
the same
across all
components in
parallel
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9V
What Is the
Voltage?
?V
?V
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Resistance
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Resistance
Resistance is anything in a
circuit that restricts the
flow of current
It can be calculated using Ohm’s Law:
Resistance
=
(Ohms)
The unit of
Resistance is the
Ohm
Voltage (V)
V
Current (A)
I
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x
R
Complete the meter readings
6A
12V
A2
A3
V1
A1
V2
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V3
Calculate the resistance
?
3A
12V
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Current-Voltage Graphs
Show Resistance
A Resistor
at constant
temperature
I
V
Different wires
have different
resistances
The current through a
resistor at constant
temperature is proportional
to the voltage
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Current-Voltage Graphs
Show Resistance
I
V
A Filament
Bulb
As the temperature
of the filament
increases, the
resistance increases –
hence the curve
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Current-Voltage Graphs
Show Resistance
Current will only flow
through in ONE
DIRECTION
I
V
A Diode
(It has very high
resistance in the
reverse direction)
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Resistance in Wires – Cross
Sectional Area
Thin wires have more resistance than
thick wires
Halving the cross sectional area of a
wire doubles its resistance because
there is half as much space for the
electrons to move
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Resistance - Length of Wire
Doubling the Length of a
wire Doubles its
resistance because the
electrons have twice as
far to move
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Resistance - Material
Different materials have different
resistances.
For Example: A nichrome wire has
more resistance than a copper wire
of the same size (the atoms in
nichrome hold the electrons more
tightly than copper atoms)
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Dark
1A
The Light Dependent
Resistor
Light
5A
The resistance of the LDR depends on
the amount of light falling on it. Its
resistance decreases as the amount of
light falling on it increases
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The Thermistor
1A
COLD
5A
WARM
The resistance of a thermistor depends
on its temperature.
Its resistance decreases as the
temperature of the thermistor increases
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Explain Fully How the
Following Work
1) A Diode
2) A Thermistor
3) A Light Dependent Resistor
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Summary: Current,
Voltage, Resistance,
Series & Parallel
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How are voltmeters & Ammeter
connected in a circuit?
A
Ammeters
are always
connected
in SERIES
Voltmeters
are always
connected in
Parallel
V
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Summary Table
Current
Is the flow of electrons
around a circuit
Voltage
Is the driving force that
pushes the current
around.
Is anything in a circuit
which slows the flow
down
Resistance
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There is a Balance….
If you increase the Voltage –
then more current will flow
If you increases the Resistance
– then less current will flow
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Which Is the Series and
Parallel Circuit
A * Current is THE SAME at any point
* Voltage SPLITS UP over each component
B
* Current SPLITS UP down each branch
* Voltage is THE SAME across each branch
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Electrolysis
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In Electrolytes the Current Is Carried by
Both Positive & Negative Charges
+The
negative
ions move
towards the
positive
electrode
- - -
+
+
- +
+
+
+
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The Positive
ions move
towards the
negative
electrode
The Process Where Current Is Carried
by Both Positive & Negative Charges Is
Called ELECTROLYSIS
+The positive
electrode is
called the
ANODE
- - -
+
+
- +
+
+
+
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The negative
electrode is
called the
CATHODE
Which way
would copper
ions move?
Electrolysis in More Detail
Each ion carries the same charge, So:
The Mass Deposited is Proportional to
the Total Charge Transferred
Charge = Current x Time
Longer
time, a greater mass is deposited
So, if a Higher Current flows for a
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Uses of Electrolysis
Depositing a metal by
electrolysis as shown
in the picture is called
ELECTROPLATING
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Lots of gold &
silver ornaments
are electroplated
because less
‘precious’ metal is
used
Submarines and Space
Vehicles use Electrolysis….
…..To split water into Hydrogen & Oxygen
• The Hydrogen is used as a fuel
• The Oxygen for breathing
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Electrolysis Questions
1) A current of 3A flows through some copper
chloride for 1 minute and 0.01g of copper is
deposited at the negative electrode.
a) How much would be deposited if the current
was increased to 6A?
b) How much would be deposited if the current
was kept at 6A and the experiment was left for
another minute?
c) How much charge flowed in question (b)
above?
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AC & DC
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Alternating Current (AC)
Voltage
The current changes
direction 50 times
every second
(frequency = 50Hz)
AC is easier to generate than DC
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Time
Direct Current (DC)
The current only
flows in one direction
Voltage
Time
If the cell is reversed
the current flows in
the opposite direction
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Household Plugs
& Fuses
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Wiring a plug
Earth Wire 3
4 Fuse
Neutral Wire 2
5 Live wire
Cable grip 1
6 Cable
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Errors in Wiring Plugs
1. Bare wires showing
2. Proper fuse not installed
3. Earth Wire not connected
4. Live & Neutral wrong way round
5. Cable Grip loose
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Dangerous Practices With
Mains Electricity
1. Broken Plugs & Frayed Cables
2. Plugs & Cables near water
3. Overloaded sockets
4. Wet hands whilst using electricity
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The Earth Wire
Earth wires are always used in
appliances with a metal case.
If a fault develops in the appliance
causing the live wire to touch the
case, there is a surge in the
current down the earth wire. This
causes the fuse to blow.
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Live & Neutral
The Live wire alternates between high
positive and high negative voltage with
an average of about 230V
The neutral wire is always at 0V.
Electricity normally flows in and out
of the live and neutral wires only
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Fuses
Symbol
Car fuses
A Fuse is a deliberate weak spot in a circuit
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How Does a Fuse Work?
Fuses are designed for
safety. If a fault develops
causing the live and neutral
(or earth) wire to cross, a
large current flows through
the fuse and causes it to
melt. This breaks the circuit
and protects the appliance
and user.
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Complete the descriptions…..
Fuse
A deliberate weak spot. Melts and breaks
the circuit with too much current
Earth Wire
Neutral
Wire
Live Wire
Cable Grip
Casing
Brass Pins
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Power & Fuses
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Power, Current & Voltage
Power is “the rate of doing work”. The
amount of power being used in an electrical
circuit is given by:
Power = voltage x current
(W)
(V)
P
(A)
The unit of power is the watt (W)
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V
X
I
Power and Fuses
Complete the following table:
Appliance
Power Rating Voltage (V)
(W)
Toaster
950
230
Electric Fan
Heater
2200
230
Hairdryer
330
230
Floor
Cleaner
1050
230
Computer
200
230
HiFi
80
230
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Current
(A)
Fuse
Required
(3, 5 or 13A)
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Charge
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How Do We Calculate ‘Charge’?
The unit of ‘Charge’ is the Coulomb (C)
We can work out how much charge flows in a
circuit using the equation:
Charge = current x time
(C)
(A)
The symbol for charge is Q
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(s)
Q
I
X
T
Questions
1) A circuit is switched on for 30s with a current of
6A. How much charge flowed?
2) During electrolysis 3A was passed through some
copper chloride and a charge of 600 Coulombs
flowed. How much time was the experiment on
for?
3) A light is switched on for 30 minutes. It works
on a current of 0.5A. How much charge flowed?
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Are Energy & Charge Linked?
The energy that flows in a circuit depends
on the amount of charge carried by the
electrons and the voltage pushing the
charge around
Energy Transferred = Charge x Voltage
(J)
(C)
E
V
X
Q
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(V)
Questions
1) A portable cd player has a voltage of 5V and a
charge of 100C flowing through it. How much
energy has been transferred?
2) A table light is attached to a 12V circuit. It has
a charge of 1200C flowing through it. If the
lamp is on for 15 minutes calculate
a) the current
b) the resistance
c) the energy supplied to the bulb.
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The Cost of Electricity
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The kiloWatt hour (kWh) is a unit
of Electrical energy.
In this case the meters are showing
how much electrical energy has been
used in a home
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How do we calculate the cost
of electricity?
This depends on:
• The POWER RATING of the
appliance and
• HOW LONG you leave it on for.
Electricity is measured in “units”, also
called “kilowatt hours” (kWh).
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For electrical devices we can use the
equation:
POWER =
(W)
Energy transformed (J)
time taken (s)
Appliances such as toasters, irons & TVs
have a power rating marked on them either in
watts or kilowatts.
1 kiloWatt (kW) = 1000 watts
1 Watt = 1 Joule per second
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Consider this kettle.
In 5 seconds, the kettle takes
10,000 Joules of energy from
the mains supply.
What is its power?
Power = Energy Transformed
Time taken
= 10,000 / 5
=
2000W (or 2kW)
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Calculate the cost of leaving a 600W
computer on for 120 minutes. (The
cost of each unit of electricity is 8
pence)
Number of UNITS used = Power (in kW) x Time (in hours)
= 0.6 kW
x
2 hours
= 1.2 units
COST of Electricity = Number of Units used x price per unit
= 1.2 units x 8 pence
= 9.6 pence
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Magnets
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What Is a Magnetic Field?
A Magnetic Field is a region
where magnetic materials (like
iron & steel) and also wires
carrying currents experience a
force acting on them
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This Is the Magnetic Field
Around a Bar Magnet
As a diagram
Underwater
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Iron Filings or Compasses
Can Be Used to Show the
Lines of Magnetic Field
The closer
the field
lines - the
greater the
magnetic
force
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This Is the Magnetic Field
Generated by a Solenoid
Can you see
the similarity
of the field
pattern with a
bar magnet?
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The Right Hand Thumb Rule
Shows Which Way the
Magnetic Field Goes
Current
Magnetic
field
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Where is the North Pole &
South Pole
Field lines go
from the
North Pole to
the South Pole
S
N
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If you look directly into one
end of a solenoid, the direction
of current flow tells you
whether it’s the North Pole or
South Pole you’re looking at
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What does the magnetic field look
like around 2 bar magnets?
N
S
N
N
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What Does a Magnetic Field
Look Like on a Horse Shoe
Shaped Magnet?
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Explain What Happens Here.
Draw the magnets and the field
patterns associated with them
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Electromagnets
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Electromagnets
An electromagnet is just a coil of
wire with an iron core. It can be
switched on and off when wished
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These Are All Electromagnets
They all have
• a DC power supply
• a soft iron core (e.g a nail) and
• a coil
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Electromagnets
The strength of an
electromagnet depends
on 3 factors:
• The size of the
current
• The number of turns
on the coil
• What the Core is
made of
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What Are The Uses Of
Electromagnets?
1) Electromagnets can
be switched on & off
they can therefore be
used to pick up (and
put down) scrap iron
and steel
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2) The Electric Bell
•When the switch is closed
the electromagnet is turned
on
• This pulls the iron arm to
the right and sounds the bell
• At the same time the
contact is broken which
immediately turns off the
electromagnets and the
•The arm swings back.…
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3) Circuit breakers
Soft Iron
Coil
Pivot
Current In
Contact
Current Out
If the current becomes too high the
electromagnet attracts the soft iron. This will
break the circuit. Circuit breakers have two main
advantages over fuses: they work quicker and can
easily be reset
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4) This is the ‘Maglev’ Train
It is levitated and pushed along silently
and smoothly by electromagnets
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5) The Loudspeaker
Permanent
magnet
Coil
Current
Cone
Vibrates
AC electrical signals from the amplifier are sent to
the coil making the coil move over the permanent
magnet. These movements make the cardboard cone
vibrate and generate the sound
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Generating Electricity
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Generating Electricity
We can generate electricity through
Electromagnetic Induction………
Electromagnetic Induction: The Creation
of a Voltage (and maybe a Current) in a
wire which is experiencing a Change in
Magnetic Field
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Electromagnetic Induction
N
The ‘field
lines’ have
to be cut.
No current
is produced
if the
magnet is
not moving!
If You push a magnet into a coil the
electrons in the coil are also given a
push. This makes an ‘induced voltage’
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Electromagnetic Induction
Notice the
needle
moves in the
opposite
direction
N
If You pull a magnet out of the coil the electrons
in the coil are once again given a push. This makes
an ‘induced voltage’ in the opposite direction
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How Can You Increase the
Size of the Induced
Current?
1. Move the Magnet Faster
2. Use a Stronger (not bigger!)
Magnet
3. Put more Turns on the Coil
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We can use a magnet, coil and
movement to generate electricity
with this device
Will it make AC or DC Current?
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This is a Generator
You will have heard them near road
works generating the electricity to make
the traffic lights and machines work
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AC Generator
Induced current can be increased
in 4 ways:
1) Increasing the speed of movement
2) Increasing the magnetic field strength
3) Increasing the number of turns on the
coil
4) Increasing the area of the coil
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Bikes often have Dynamos to make
electricity to light a bulb
Dynamos are slightly
different from
generators as they
rotate the magnet
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If the Needle on the Centre Spot
Galvanometer Moves Right 1 Division
When the Magnet Is Placed Into the Coil,
What Happens When….
1) The magnet is pulled out at equal speed?
2) The magnet is put in faster?
3) The magnet is left motionless inside
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the coil?
1) Explain what happens when
the handle turns at a constant
rate
Use the Key Words
in your answer:
Magnet, coil,
flux, a.c, bulb
shines, movement
2) Give 3 methods to increase the
brightness of the bulb
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The Electric Motor
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The Electric Motor
The Electric Motor is designed
to change electrical energy
into movement energy.
It Can do this because…….
Anything carrying an electric current
in a magnetic field experiences a
force
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Lots of Machines Need
Motors to Work
The motors we use in
science may look like
this
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Force
The Simple
Electric Motor
S
Split Ring
Commutator
N
Force
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The Simple Electric Motor
The 4 factors which speed it up are:• More Current
• More Turns on the Coil
• A Stronger Magnetic Field
• A Soft Iron Core in the Coil
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The Simple Electric Motor
– How Does It Work?
Because there is a current in a magnetic
field there is a force produced. The
force acts on the two side arms of the
coil and causes it to rotate on the
spindle.The split ring commutator is a
clever way of swapping the contacts
every half turn to keep the motor
rotating in the same direction
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How Can We Reverse the
Direction of the Motor?
1. Swap the polarity of the D.C.
Supply
2. Swap the Magnetic Poles over
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Fleming’s Left Hand Rule
Tells You Which Way the
Force Acts
thuMb
Motion
First finger
Field
seCond finger
Current
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Transformers
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Transformers
Transformers transform
(change) the Voltage
Transformers only work on AC
because there is constantly
changing flux
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Step Up & Step Down
Primary
Coil
Secondary
Coil
Primary
Coil
Secondary
Coil
Step Up
Transformer
Step Down
Transformer
More turns on
the Secondary
Coil
More turns on
the Primary
Coil
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Some Transformers Look
Like This…..
…..you might have heard
their characteristic ‘hum’
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The Transformer Equation
Primary voltage =
Secondary voltage
Number of turns on Primary
Number of turns on Secondary
The ratio of the turns on the coils
equals the ratio of their voltages
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Complete the table
Primary
Voltage
Secondary No. of
No. of
Step Up
Voltage
Turns on Turns on or Step
Primary Secondary Down?
12V
36V
100
?
?
600V
300V
20
?
?
20,000V
50,000V
1,000
?
?
23V
230V
150
?
?
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Power Stations
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What is a power station?
Power Stations are
places where
electrical energy
is made. Electrical
Energy is a
convenient form of
energy to use in
our homes.
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Fossil Fuel Power Stations
Can Generate A Lot Of
Pollution
In the form of carbon dioxide,
sulphur dioxide and smoke
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The sulphur dioxide can lead
to the production of acid rain
It can damage
leaves
And whole
forests
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The National
Grid
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What is the National Grid?
When electricity is generated in the
power station it is transported to us by
the National Grid
It is a network of
pylons and cables
that covers the
whole country
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The National Grid
Power
Station
25,000V
Step-down
Transformer
Step-up
Transformer
400,000V
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Homes
230V
Why Do We Step Up the
Voltage?
Transmission cables can be hundreds of
kilometres long. This means that energy
is wasted because of the heating effect
of the current.
By using a transformer to increase the
voltage, the current is reduced, so
thinner, lighter & cheaper cables can be
used
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Resistance & Power Loss
When a current flows through a
conductor it has a heating effect so
power is wasted. The power loss can be
calculated like this……
Power Loss
= Current2 X Resistance
Power Loss is reduced significantly if
the current is reduced
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Related Websites
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Electrical circuits
http://www.miamisci.org/af/sln/frankenstein/safety.
html - Interactive ‘clickable’ diagram about electrical
safety.
http://www.bbc.co.uk/apps/ifl/schools/gigaquiz?path
=ks3bitesize/elecmag1tb
&infile=elecmag1tb and
http://www.bbc.co.uk/apps/ifl/schools/gigaquiz?path
=ks3bitesize/elecmag2tb&infile=elecmag2tb Activities about electrical circuits,
http://www.crocodile-clips.com/m6_4.htm - Download
free software called crocodile-clips, which allows you
to create virtual circuits. (Has worksheets also)
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http://www.brainpop.com/science/electricity/elect
ricity/ - Electricity in general rather than circuits
specifically - excellent for putting it all in context
(movie and quiz).
Pages from How Stuff Works explaining basic
electrical items:
http://home.howstuffworks.com/toaster.htm
(toaster)
http://home.howstuffworks.com/burglar-alarm.htm
(burglar alarm)
http://home.howstuffworks.com/doorbell.htm
(doorbell)
http://home.howstuffworks.com/dimmerswitch.htm (dimmer switch)
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Energy and electricity
http://www.article19.com/shockwave/ph.htm - This
interactive house lets you turn on household
electrical items and see the immediate effect on your
electric bill.
http://www.miamisci.org/af/sln/frankenstein/static.
html - Info on static electricity and how to generate
it and
http://www.bbc.co.uk/schools/gcsebitesize/physics/
electricity/
electricchargeandcurrentrev4.shtml some great
images/animations from BBC Bitesize.
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http://www.brainpop.com/science/electricity/
electricity/ (electricity)
http://www.brainpop.com/science/energy/ (all
BrainPOP energy-related topics)
http://www.phy.hr/~dpaar/fizicari/xfaraday.ht
ml - Biography of Michael Faraday (known for
his electricity and magnetism experiments)
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Magnets and electromagnets
http://www.brainpop.com/science/forces/magnetism/
- movie and quiz on magnetism
http://www.brainpop.com/science/forces/magneticpo
les/ - on magnetic poles.
http://education.magnet.fsu.edu/maglabalpha/html/e
xpeditions/
whatmagnet.html - text-based information on
magnets and
http://www.phys.lsu.edu/dept/opps/key_ideas_about
_magnets.htm lots of key facts about magnets (good
for research).
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http://science.howstuffworks.com/electromagnet.htm
- Electromagnets, from How Stuff Works (includes
useful animation) and
http://electronics.howstuffworks.com/speaker.htm
how speakers work (may be handy for research –
speakers contain electromagnets).
http://www.bbc.co.uk/apps/ifl/schools/gigaquiz?path=
ks3bitesize/elecmag2tb
&infile=elecmag2tb - test on electromagnets (and
electrical circuits) from BBC Bitesize.
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http://www.zephyrus.co.uk/whataremagnets.html Good, simple explanation of what a magnet is in
terms of lots of aligned polar molecules.
http://www.units.muohio.edu/dragonfly/find/find/
compass.htmlx - info about compasses and how to
make your own compass.
No Messing Resources c
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