Transcript electricity

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1. Fossil fuel is burnt
2. The heat turns water to
steam
3. The steam turns a turbine
4. The turbine turns a generator
5. This induces a current and
creates electricity
Electricity from a power station goes to:
1. Step-up transformers – increases the voltage which
decreases the current and reduces energy loss
2. High voltage transmission lines
3. Step-down transformers – decrease the voltage to
make it safe for us to use
4. Consumers, for example homes, factories and shops.
All of these methods are used to heat water to create
steam which is used to turn the turbine and generate
electricity
Energy source
Advantages
Disadvantages
Coal
Relatively cheap to
mine, ready made
fuels
Non-renewable,
burning produces
CO2
Oil
Short start-up time,
ready made fuels
Non-renewable,
burning produces
CO2
Gas
Slightly cleaner fuel than Non-renewable,
oil and gas and is a ready burning produces
made fuel
CO
2
Nuclear power
Produces lots of
energy, does not
produce CO2
Non-renewable,
produces dangerous
nuclear waste
1. Wind, hydroelectricity and geothermal all turn a
turbine which will create electricity
2. Solar cells use light to create electricity
Energy source
Advantages
Disadvantages
Wind
Renewable, no fuel
costs
No wind sometimes,
noisy
Hydroelectric
Renewable, no fuel
costs
Can flood areas,
disrupts habitats
Solar
Renewable, no fuel
costs
No sun at night, some
countries don’t get
enough sun in the
day, panels are
expensive
Geothermal
Renewable, no fuel
costs
Only available in
volcanic regions,
Power stations fuelled by fossil fuels or nuclear fuels are reliable
sources of energy. This means they can provide power
whenever it is needed.
1.
2.
3.
4.
gas-fired station (shortest start-up time)
oil-fired station
coal-fired station
nuclear power station (longest start-up time)
Nuclear power stations and coal-fired power stations provide
'base load' electricity - run all the time as they take the longest
time to start up.
Oil-fired and gas-fired power stations are often used to provide
extra electricity at peak times, because they take the least time
to start up.
The fuel for nuclear power stations is relatively cheap, but the
power stations themselves are expensive to build. It is also very
expensive to dismantle old nuclear power stations and to
store their radioactive waste, which is a dangerous health hazard.
Wave energy - the rise and fall of the water
(kinetic energy) drives generators and makes
1. Be able to draw and label a block diagram of a
electricity
power station showing the main parts.
2. Be
able to– distinguish
the goes
difference
between
Tidal
energy
when the tide
in and
out,
and tides.
therewaves
is a large
amount of kinetic energy. This
3. Be
able toadescribe
the advantages
and
goes
through
tidal barrage
that contains
disadvantages
of solarelectricity
cells.
generators
which makes
4. Understand that to prevent carbon dioxide
building
up inand
thestorage
atmosphere
can catch
it
Carbon
capture
stopswe
carbon
dioxide
and up
store
of the best
natural containers
building
in it.
theSome
atmosphere.
It involves
are old carbon
oil and gas
fields.
separating
dioxide
from waste gases. The
5. Be able
to identify
label
a diagram offor
the
carbon
dioxide
is then and
stored
underground,
main in
parts
National
example
old of
oil the
fields
or gasGrid.
fields.
 Waves
are vibrations that transfer energy
from place to place without matter (solid,
liquid or gas) being transferred.
 Some
waves must travel through a
substance. The substance is known as the
medium and it can be solid, liquid or gas.
 In
transverse waves, the oscillations
(vibrations) are at right angles to the
direction of travel and energy transfer
 Light
and other types of electromagnetic
radiation are transverse waves. All types of
electromagnetic waves travel at the same
speed through a vacuum, such as through
space.
 In
longitudinal waves, the oscillations are
along the same direction as the direction of
travel and energy transfer.
 Sound
waves and waves in a stretched
spring are longitudinal waves.
 The
wavelength of a wave is the distance
between a point on one wave and the same
point on the next wave.

The frequency of a wave is the number of
waves produced by a source each second. It is
also the number of waves that pass a certain
point each second.
 The
speed of a wave is related to its frequency
and wavelength, according to this equation:
v=f×λ
v
is the wave speed in metres per second, m/s
 f is the frequency in hertz, Hz
 λ (lambda) is the wavelength in metres, m.
The angle of incidence equals the angle of reflection
 Sound waves and light waves reflect from surfaces.
 Smooth surfaces produce strong echoes when sound
waves hit them, and they can act as mirrors when
light waves hit them. The waves are reflected
uniformly and light can form images

Rough surfaces scatter sound and light in all
directions. However, each tiny bit of the surface still
follows the rule that the angle of incidence equals
the angle of reflection
Sound waves and light waves change speed when
they pass across substances with different densities.
 This causes them to change direction and this effect
is called refraction.
 Refraction doesn't happen if the waves cross the
boundary at an angle of 90°(the normal) - they carry
straight on.

When waves meet a gap in a barrier, they carry on
through the gap and spread out
 How much they spread out depends on how the width
of the gap compares to the wavelength of the waves.
 Lots of diffraction happens when the wavelength is
the same size as the gap.

A gap similar to the wavelength causes a lot of
spreading with no sharp shadow, e.g. sound through a
doorway
 A gap much larger than the wavelength causes little
spreading and a sharp shadow, e.g. light through a
doorway.

Sound waves and light waves change speed when
they pass across substances with different densities.
 This causes them to change direction and this effect
is called refraction.
 Refraction doesn't happen if the waves cross the
boundary at an angle of 90°(the normal) - they carry
straight on.

Longitudinal waves
 Echoes are reflections of sound waves
 Sound can only travel in a solid, liquid or gas
 A loud sound has a high amplitude
 A quiet sound has a small amplitude
 A high pitched sound has a high frequency
 A low pitched sound has a low frequency
 The normal range of human hearing is between about
20 Hz and 20 kHz
 The range becomes less as we get older.
 Sounds with frequencies above about 20 kHz are
called ultrasound.

Contains 7 different types of radiation
Longest wavelength
Shortest frequency
Shortest wavelength
Highest frequency
Used for TV and radio
 TVs use higher frequencies than radios
 Diffraction allows radio signals to be received
behind hills and repeater stations are used to
improve reception

Used to transmit signals such as mobile phone calls.
 Microwave transmitters and receivers on buildings
and masts communicate with the mobile telephones
in their range.

Some mobile phones may be a
health risk.
 Others think that the intensity of
the microwaves is too low to
damage tissues by heating, and
microwaves are not ionising.
 Some wavelengths can be used to
transmit information to and from
satellites in orbit. Satellite TV
signals use microwaves.

VISIBLE LIGHT
Visible light helps us to communicate via sight
 Cameras and video recorders use visible light
 Very bright light damages our eyes

INFRARED
Infrared is used in toasters,
heaters and grills and can cause
burns
 Used in burglar alarms, remote
controls and security alarms

Examiner’s tip
 Be
able to construct a ray diagram to show the
image formed by a plane mirror.
 Know the order of the electromagnetic waves
within the spectrum in terms of energy,
frequency and wavelength.
 Be able to complete diagrams for wave fronts
showing reflection, refraction and diffraction.
 Learn the units of the terms in the equation and
know how to convert kilohertz to hertz.
 Know how radio waves, microwaves, infrared and
visible light can be used in communications.
 Know the relationship between pitch and
frequency.
Learning
Outcomes:
Good- know the
key facts in the
physics module
EBI- You can
apply what we
recap to past
paper questions
Excellent- You
can get 75% of
marks in each
question
The next few slides will give
you all of the information
that you need for a question
about the origins of the
Universe.
Make sure you make a note of
anything that you’re not
sure of
Learning
Outcomes:
Good- know the
key facts in the
physics module
EBI- You can
apply what we
recap to past
paper questions
Excellent- You
can get 75% of
marks in each
question
Examiner’s tip
Be able to explain the
term ‘red-shift’ and the
‘Big Bang’ theory.
 Theory
– an idea but not a fact
 The theory states that originally all the matter
in the universe was concentrated into a single
incredibly tiny point.
 This began to enlarge rapidly in a hot explosion
(called the Big Bang), and it is still expanding
today.
 The Big Bang happened about 13.7 billion years
ago
 Cosmic
microwave background radiation (CMBR)
– thought to be left over heat from the original
explosion
 Doppler
effect
 Red-shift
When a police car goes past, its siren is high-pitched
as it comes towards you, then becomes low-pitched
as it goes away.
 When a source (e.g. galaxy) moves towards an
observer, the observed wavelength decreases and the
frequency increases.
 When a source (e.g. galaxy) moves away from an
observer, the observed wavelength increases and the
frequency decreases.


When an object (e.g. galaxy) moves away from an
observer, its light is affected by the Doppler effect

We know our sun has helium in it because there are
black lines in the spectrum of the light from the Sun
where helium has absorbed light. These lines form the
absorption spectrum for helium.

When we look at the spectrum of a distant star, we still
see an absorption spectrum. However, the pattern of
lines has moved towards the red end of the spectrum,
as you can see above.

The positions of the lines have changed because of
the Doppler effect. Their wavelengths have increased
and their frequencies have decreased.

The further from us a star is, the more its light is
red-shifted. This tells us that distant galaxies are
moving away from us, and that the further away a
galaxy is, the faster it's moving away.

Red shift tells us how far away a galaxy is and the
speed at which it is getting further away from us