GCSE Edexcel P1 Review

1. P1.1 The Solar System
• Geocentric model = Ptolemy =
explained the Sun, moon and the
planets move in orbits and that
Earth was at the centre.
• Heliocentric model = Copernicus=
sun was at the centre and everything
went round the Sun.
• Church = did not like Copernicus
idea.
• Galileo = used telescope to prove
Copernicus was right.
Ideas about the solar system have changed over time
Galileo observed Jupiter’s moons. By plotting their positions he provided more evidence for
the heliocentric model.

2. P1.1 The Solar System
How do we know about the Solar System and the Milky Way?
• Telescope = observe space - advantage see more then just with the
naked eye.
• Luminous Objects = give out light that travels as a wave.
• Non luminous objects = give out waves such as Radio waves and
microwaves.
We can detect these waves.
As telescopes improved, more planets were discovered
Comparing different ways of looking at space…
1. Telescopes provide greater magnification than the naked eye.
2. Telescopes provide continuous images.
3. Photographs provide a picture from one moment in time.
4. Photographs can be studied at a later date.
5. You need a way to capture telescope images to preserve them.

3. P1.2 Refracting telescopes
Key words:
• Lens - a transparent block that causes light to refract
• Refraction – changes the direction the light travels in. It occurs when light passes from one
substance to another e.g. air and glass.
• Converging lens (or convex lens) - is curved on both sides. This means the light rays coming out of it
come together at a point – they converge.
• Focal point – the point at which light rays meet.
Measuring the focal length
The focal length is found by
focussing a distant object on a
piece of paper through the lens.
The focal length is the distance
between the centre of the lens and
the image.
A converging lens is used in
a refracting telescope to focus the
image. Galileo’s telescope would
have been a refracting telescope.
Waves are always refracted at boundaries
between different materials

4. P1.2 Refracting telescopes
1. A refracting telescope works bending light through a lens so that it forms
an image.
2. Large lenses are needed to improve the magnification.
3. The objective lens focuses the light to the focal point of the lens.
4. This point is also the focal point of the more powerful eyepiece lens.
5. The eyepiece lens produces a magnified image of the image from the
objective lens which the viewer can see.
You don’t need to draw
this diagram but you do
need to explain how the
eyepiece lens enlarges
the image

5. P1.2 Refracting telescopes
Refraction
• Light waves change speed when they
pass across the boundary between
two substances with different
densities, such as air and glass.
• This causes them to change
direction and this effect is
called refraction.
• There is one special case you need to
know. Refraction doesn't happen if
they cross the boundary at an angle
of 90° - in that case they carry straight
on.
normal
normal
incident
ray
refracted
ray
Refracting telescopes need to be long in order to have large magnification.

6. P1.3 Lenses
Converging lenses
Their magnification is affected by
• How curved they are
• How close together the lenses are
A real image can be projected onto a screen.
A virtual image is seen on a mirror and cannot
be projected.

7. Reflecting telescope.
In order to collect as much light as
possible, the objective lens needs a large
diameter.
Large lenses are very difficult to make
and so are very expensive.
Reflecting telescopes overcome this by
using relatively cheap mirrors as their
objective.
These can be made extremely large.
P1.4 reflecting
telescope
How they work…
• Reflecting telescopes have a
curved mirror instead of an
objective lens.
• The primary mirror focuses
parallel light rays from a
distant object.
• The eyepiece lens magnifies
this image

8. P1.5 Waves
Key definition:
Waves transfer energy and information without transferring
matter.
Key words:
Wavelength – The
distance from one peak
(or trough) to the next.
Frequency – The number
of waves passing a point
per second.
Amplitude – the maximum
distance of particles in a
wave from the normal.
2 equations you need to be able to
use:
Wave speed = frequency x wavelength
Wave speed = distance/time

9. P1.5 Waves
Longitudinal waves e.g. sound
waves.
Transverse waves e.g.
electromagnetic waves , don’t
need a medium to travel
through.
Seismic waves can be
longitudinal (when the crust
moves back and forth, or
transverse when the crust moves
up and down.

10. P1.6 Beyond the visible
• Herschel put dark coloured
filters on telescope to observe
the Sun.
• He noticed that the filters
heated up the telescope to
different extents.
• He used a prism to test this
and put thermometers in each
colour of light.
• As he moved from violet to
red, the temperature
increased.
• Just beyond the red was even
hotter.
• He discovered infra red waves.
• Ritter investigated the violet
end of the spectrum.
• He put silver chloride at each
end of the spectrum. It turned
black more quickly at the
violet end than the red end.
• It turned black even more
quickly just beyond the violet.
• This was called ultraviolet
waves.
All electromagnetic waves are
transverse.
They transmit energy at right angles
to the direction of the vibration.
Know these two
scientists and their
work!

11. P1.7 The Electromagnetic SpectrumLearntheseinorder
• All electromagnetic waves are transverse.
• All electromagnetic waves travel at the same speed in a
vacuum.
• The electromagnetic spectrum in continuous from radio
waves to gamma rays
• The different radiations are grouped in order of
decreasing wavelength and increasing frequency

12. P1.8 electromagnetic dangers
• The higher the frequency the more energy that they
carry.
• High-frequency electromagnetic waves, such as
gamma rays, are potentially more harmful because
they have more energy.
All waves transfer energy.
Bodies are made of mostly
water - waves can heat water.
At the moment there is no
evidence to support mobile
phones could be harmful to the
body
IR radiation used in grills and
toasters.
Our skin absorbs IR = makes us
warm.
Too much can cause burns to
the skin.
Wave Effect on the body
Microwaves Internal heating of body cells
Infra red Burns skin
Ultraviolet Damage to surface cells and
eyes leading to skin cancer and
eye conditions
X-rays and
gamma rays
Causes mutations and damage
to cells in the body

13. P1.9 using electromagnetic radiation
Electromagnetic Radiation Use
Radio waves Broadcasting, communication and
satellite transmissions
Microwaves Cooking, communications and satellite
transmissions
Infra red Cooking, thermal imaging short range
communication, optical fibres, television
remote controls, security systems
Visible Vision, photography, illumination
Ultraviolet Security marking, fluorescent lamps,
detecting forged bank notes, disinfecting
water
X-rays Observing internal structure of objects,
airport security scanners, medical x-rays
Gamma rays Sterilising food and medical equipment,
detection of cancer, treatment of cancer

14. P1.10 Ionising radiation
• Ionising radiation is emitted all the time by radioactive sources.
• Ionising radiation includes alpha and beta particles and gamma rays.
• These three types of ionising radiation transmit energy and can all damage
cells.
• It is called ionising as it removes electrons from atoms to form ions.
• Ions are very reactive and if there are a lot of them in cells, they can
damage DNA.

15. P1
Topic 3 Waves and the Universe

16. P1.11 The Universe
Keywords
• Star – a large ball of gas that produces heat and light energy from fusion reactions
• Milky Way– The name of our galaxy
• Nebula – a cloud of gas in space. Some objects that look like nebulae are actually cluster of stars or
other galaxies
• Solar system– an area of space in which object are influenced by the Sun’s gravity
• Galaxy– a group of millions of stars held together by gravity
• Universe– all the stars, galaxies and space itself
Facts:
• The moon is 30 ‘earths’ away
• The sun is 11,000 ‘earths’ away
Ancient astronomers observations / ideas:
1. Stars further away than planets
2. Stars in a shell around earth at the same distance
3. Saw patches of ‘fuzz’ light (nebulae)
4. Band of light across the sky = Milky Way
Galileo
1. Used basic telescopes but could only see 6 planets
Modern observations:
1. 8 planets plus dwarf plants, many moons and asteroids
2. Sun is one of millions of stars in the galaxy (Milky Way)
3. Billions of other galaxies
4. All these galaxies make up the universe

17. P1.12, 1.13 – Spectrometers and Exploring the Universe
Keywords
• Spectrum – The range of colours between red and violet obtained when white light is split using a prism.
• Spectrometer – An instrument that can split up light to show the colours of the spectrum
• Visible light – Electromagnetic waves that can be detected by the human eye
• Electromagnetic spectrum – The entire frequency range of electromagnetic waves
• X-ray – electromagnetic radiation that has a shorter wavelength than UV but longer than gamma rays
• Ultraviolet– electromagnetic radiation that has a shorter wavelength that visible light but longer than X rays
Facts
Light from the sun is a mixture of
different colours.
Each colour light has a different
wavelength and frequency.
They can be split with a prism or
something with lots of lines like a CD
or DVD.
A device that can split different
wavelengths is called a spectrometer
The atmosphere absorbs some
wavelengths so they never reach
earth.
Telescopes
• Early telescopes detected only visible light
• Modern telescopes detect all parts of the Electromagnectic spectrum (see
diagram above)
• Hubble Space telescope – in orbit around earth since 1990
– Clear images as it is above the atmosphere so does not get
interference from clouds and dust

18. P1.14 –Alien Life?
Keywords – (all from previous slide B1.12 and 1.13 also needed)
• Landers – a space vehicle that lands on a planet or a moon
• Space probes – a space vehicle that can be put into orbit around a planet or moon, or parachuted down through the
atmosphere.
• Rovers– a space vehicle that can move about on a planet or moon.
• SETI - Search for Extraterrestrial Intelligence)
Investigating the Solar System
Earth is the only place where we know life exists.
• Viking landers have been to mars
• Analysed soil for evidence of life
• No evidence discovered
• Water is needed for life
• Space probes orbiting Mars have detecting
channel caused by water flowing
• Rovers used to take close up photographs
Beyond the Solar System
• Planets discovered orbiting other stars
• They are too far away to get clear images
• Oxygen in the atmosphere would be proof of
life.
SETI
• A project that analyses radio waves coming
from space.
• Looks for signals that could be from intelligent
being.
• No messages detected yet.

19. P1.15 Life cycles of stars
Keywords
• Protostar – A cloud of gas drawn together by gravity that has not yet started to
produce its own energy.
• Fusion reaction– when the nuclei of two atoms join together and release energy
• Red giant– A start that has used up all the hydrogen in its core and is now using
helium as a fuel. It is bigger than a normal star.
• White dwarf– A very dense star that is not very bright. A red giant turns into a
white dwarf.
• Supernova – An explosion produced with the core of a red supergiant collapses.
• Red Supergiant– A star that has used up all the hydrogen in its core and has a
mass much higher than the Sun.
• Black hole– Core of a red supergiant that has collapsed. Only created when the
remaining core has a mass 3-4 times that of the sun.
• Neutron Star– Core of a red supergiant that has collapsed.

20. Nebula
• Suns remain stable for
billions of years.
• As the nebula heat up it
glows
• More mass attracted
which increases gravity
and compresses material
into a protostar.
Protostar
• Temperatures and
pressure increase.
• Hydrogen nuclei fuse to
make helium.
• Fusion reactions release
energy as EM radiation.
MAIN SEQUENCE of the life
cycle
Massive stars
• Hotter and brighter
• Fusion reactions are faster
• Become red supergiants
• Rapidly collapses and explode
(supernova)
Red Giant
• Once most Hydrogen fused the star is not hot
enough to withstand gravity and collapses
• Forms a Red giant
Supernova
• Outer layers cast off and expand outwards
• Two options
1. If 3-4 times heavier than the sun = Black hole (gravity so strong
not even light can escape)
2. Anything smaller forms a neutron star.
White Dwarf
• Star is Red giant for billions of years
• Gas shell thrown off so it collapses into a white
dwarf.
• Cools slowly to become a black dwarf.P1.15 Life cycles of stars
(cont’d)

21. P1.16 Theories about the Universe
Light moving away from us is detected with a
longer wavelength than expected. It is shifted
towards the Red end of the spectrum = RED SHIFT
Light from other galaxies does this showing they
are moving away from us.
UNIVERSE IS EXPANDING
STEADY STATE THEORY
1. Universe always existed and is expanding
2. New matter continuously created so it always
looks the same
3. Red shift supports this theory as well as the
Big Bang theory.
4. No longer accepted theory
BIG BANG THEORY
1. Start - Tiny point of concentrated energy
billions of years ago
2. All matter existed at this point
3. Expanding from this point
4. Gravity caused matter to clump forming
stars
5. Cosmic Microwave Background (CMB)
radiation (microwave signals from all over
the sky) provided proof for the Big Bang
Theory
6. Accepted theory today

22. P1.17 – Red shift
Keywords
Red Shift– waves emitted by something moving away from an observer have their wavelength increased
and frequency decreased compared to waves from a stationary object.
Doppler Effect – the change in pitch of a sound coming from a moving source
Pitch – whether a sound is high or low
1. Sound waves behind a moving
source become stretched
making the frequency lower
and the wavelength longer.
Similar effect occurs in RED
SHIFT
2. VISIBLE SPECTRUM contains
gaps. If they are red shifted
the star is moving away from
us
3. Further away galaxies are
moving the fastest

23. P1
Topic 4 Waves and the Earth

24. P1.18 – Infrasound
Keywords
Frequency – number of complete waves that pass a point in one second
Hertz – unit of measurement for frequency
Longitudinal waves– the direction of energy is parallel to the direction of vibration which
causes them
Infrasound – sound with frequency below 20Hz (cannot be heard)
Uses of infrasound
1. Studying animal movements
a) Elephants, whales and giraffes communicate using infrasound
b) Animals can be tracked in difficult areas (forests)
2. Monitoring volcanoes
a) Infrasound travels a long way
b) Used to monitor volcanoes in remote locations from a distance
3. Detecting meteors
a) Some enter atmosphere unseen
b) Helps us determine how many enter and the risks of impact

25. P1.19 – Ultrasound
Ultrasound
• Humans detect sound waves between 20 – 20,000Hz
• Above 20,000Hz = Ultrasound
• Some animals use it to communicate (dolphins)
Sonar
• Used by some animals (bats) to detect obstacles
• Ultrasound waves made by animals reflect as echoes
• Used by humans in ships to detect fish, sea depth
Equation
Distance (m) = speed(m/s) x time (s)
Ultrasound Scan
• Make images of things inside the body
• Example of use – to scan an unborn baby to check development
– different parts of the baby reflect the sound in different
ways to create the image on the screen.
Keywords
Ultrasound – sound waves with a frequency above 20,000Hz, which is
too high for the human ear to detect.
Sonar – a way of determining distance to an object by timing how long it
takes for a pulse of ultrasound to be reflected.
Reflected – when a wave bounces off a boundary between two materials

26. P1.20 – Seismic
waves
• Movements inside the earth cause seismic
waves to be transmitted
• When waves reach the surface = ground shakes
• Seismometers detect these waves
• Place where the original movement or fracture
occurs = focus and the epicentre is the surface
directly above the focus.
Investigating the Earth
• Scientists investigate waves but setting
controlled explosions or dropping masses from a
truck
• The waves reflect and refract giving information
about the rocks below
• Used to look fro oil or locate changes in rock
type.
• Seismic waves – Waves produced by an explosion or earthquake and
which travel through the earth.
• Focus (of earthquake) – the place where an earthquake begins
(usually under the surface)
• Epicentre – The point on the surface of the Earth directly above the
focus of an earthquake
• P waves – Longitudinal seismic waves that travel through the earth
• S waves – Transverse seismic waves that travel through the earth

27. P1.21 and 1.22 – Earthquakes and Detecting Earthquakes
Keywords
Tsunami – a huge wave caused by an earthquake or landslide on the sea bed
Tectonic Plates – Pieces of the surface of the Earth, which can move around very slowly
Convection currents – a current caused by parts of a fluid being at a different temperature and so a
different density to the rest of the fluid.
Detecting earthquakes
1. Network of seismometers around
the world
2. Calculate the arrival times of
different waves (P and S) to work out
epicentre of earthquake
Predicting earthquakes and tsunamis
1. Use plate boundaries to predict likely
locations
2. Cannot measure the forces moving
plates or the friction which makes
predicting earthquakes difficult.
3. An earthquake under the sea causes a
huge wave (Tsunami)
4. Tsunami warning systems include
pressure sensors to detect waves
5. Seisometer traces do not give warning
6. Tsunamis travel at different speeds so
this can give an opportunity for warnings
to be given.
Earthquakes
1. Outer layer of earth = tectonic plates
2. They are pushed slowly by
convection currents in the mantle
3. Friction between them stops the
movement until the force gets big
enough and a jerk happens =
earthquake

28. 1.23 Renewable resources for
electricity
Key words:
• Current – the flow of charge.
• Voltage – electrical pressure giving a measure
of the energy transferred.
• Renewable energy source – will not run out.

29. Type of energy Advantages Disadvantages
Solar •Potentially infinite energy supply.
•Single dwellings can have own electricity supply.
•No harmful gases produced.
•Manufacture and implementation of solar panels
can be costly.
Wind •Can be found singularly, but usually many together
in wind farms.
•Potentially infinite energy supply.
•No harmful gases produced.
•Manufacture and implementation of wind farms
can be costly.
•Some local people object to on-shore wind farms,
arguing that it spoils the countryside.
Tidal •Ideal for an island such as the UK.
•Potential to generate a lot of energy.
•Tidal barrage can double as a bridge, and help
prevent flooding.
•No harmful gases produced.
•Construction of barrage is very costly.
•Only a few estuaries are suitable.
•Opposed by some environmental groups as having a
negative impact on wildlife.
•May reduce tidal flow and impede flow of sewage
out to sea.
Wave •Ideal for an island country.
•More likely to be small local operations, rather than
done on a national scale.
•No harmful gases produced.
•Construction can be costly.
•May be opposed by local or environmental groups.
Geothermal •Potentially infinite energy supply.
•Used successfully in some countries, such as New
Zealand and Iceland.
•No harmful gases produced.
•Can be expensive to set up and only works in areas
of volcanic activity.
•Geothermal and volcanic activity might calm down,
leaving power stations redundant.
•Dangerous elements found underground must be
disposed of carefully.
Hydrological or
Hydroelectric
Power (HEP)
•Creates water reserves as well as energy supplies.
•No harmful gases produced.
•Costly to build.
•Can cause the flooding of surrounding communities
and landscapes.
•Dams have major ecological impacts on local
hydrology.

30. P1.24 Non-renewable resources
Type of fuel Advantages Disadvantages
Coal (fossil fuel) •Ready-made fuel.
•It is relatively cheap to mine and to convert
into energy.
•Coal supplies will last longer than oil or gas.
•When burned coal gives off atmospheric
pollutants, including greenhouse gases.
Oil (fossil fuel) •Oil is a ready-made fuel.
•Relatively cheap to extract and to convert
into energy.
•When burned, it gives off atmospheric
pollutants, including greenhouse gases.
•Only a limited supply.
Natural gas
(fossil fuel)
•Gas is a ready-made fuel.
•It is a relatively cheap form of energy.
•It's a slightly cleaner fuel than coal and oil.
•When burned, it gives off atmospheric
pollutants, including greenhouse gases.
•Only limited supply of gas.
Nuclear •A small amount of radioactive material
produces a lot of energy.
•Raw materials are relatively cheap and can
last quite a long time.
•It doesn't give off atmospheric pollutants.
•Nuclear reactors are expensive to run.
•Nuclear waste is highly toxic, and needs to
be safely stored for hundreds or thousands of
years (storage is extremely expensive).
•Leakage of nuclear materials can have a
devastating impact on people and the
environment. The worst nuclear reactor
accident was atChernobyl, Ukraine in 1986.

31. P1.26 Generating Electricity
Factors that affect the size of an induced current:
• Using a coil of wire or increasing the number of
turns on the coil.
• Use an iron core.
• Use a stronger magnet.
• Move the wire faster.
Factors that affect the direction of an induced
current:
• The direction of the movement of the wire.
• The direction of the movement og the magnet.

32. P1.26 Generating Electricity
Key words:
• Direct Current (D.C.) – A current that flows in one direction.
• Alternating Current (A.C) – A current whose direction changes many
times a second.
• Electromagnetic Induction – The process of making a current in a wire
as it is passed through a magnetic field.
• For a continuous current, the wire or the magnet must be continually
moving.
• In a power station, a large current needs to be induced.
• Electromagnets are used as they are more powerful than permanent
magnets.

33. P1.26 Generating Electricity
A Generator
• Current is induced in the
coil. And transferred to a
circuit through the slip
rings which touch carbon
brushes.
• As the coil turns the
direction of the induced
current changes.
• Alternating Current (A.C.)
is induced

34. P1.26 Generating Electricity
A Dynamo
• Used to produce
electricity to power cycle
lights.
• Magnet spins inside a coil
of wire
• A current is induced.
• Direct current (D.C)
• Other examples are wind
up torches or radios.

35. P1.27 Transmitting Electricity
Key words:
• Transformers – change the size of an alternating
voltage.
• Step up transformer – increases the voltage
• Step down transformer – decreases the voltage
Electricity is transmitted at high voltages as it
increases efficiency by reducing heat loss in the
power lines.

36. P1.27 Transmitting Electricity
• A transformer consists
of two coils wrapped
around an iron core.
• Electricity is supplied
to the primary coil
and obtained in the
secondary coil at a
different voltage.
You need to be able to use this formula to work out the turns of
the voltage:
Try these examples…

37. P1.27 Transmitting Electricity
Hazards of electrical transmission
• High voltages are likely to kill.
Voltage increased to
400,000V to reduce
heat loss
Voltage reduced to
33,000V for factories
Voltage reduced to
230/240V for homes

38. P1.28 Paying for Electricity
Key words:
• Power – the energy
transferred per second.
Measured in watts (W)
• Energy from the mains
supply is measured in
Kilowatt-hours (Kwh)
What is the power if the
voltage is 12V and the
current is 5A?
power = 5 × 12
= 60W
Formula 1
3 formulae you
need to know…

39. P1.28 Paying for Electricity
• Electricity meters measure the
number of units of electricity used
in a home or other building. The
more units used, the greater the
cost. The cost of the electricity
used is calculated using this
equation:
• cost = power (kW) × time (hour) ×
cost of 1 kWh (pence)
How much energy is used by a
2000W appliance running for 60
seconds?
power = 2000 × 60
= 120000
An electric fire needs 2 kW. It is
switched on for 3 hours. If each kWh
costs 10p, how much does it cost to
run the fire?
cost = power × time × cost of 1 kWh
= 2 kW × 3 h × 10p
= 60p
Formula 2
Formula 3

40. P1.30 Reducing energy use
Disadvantages of low energy appliances:
• initial cost
• use of extra resources to manufacture new
device
• cost of disposal of old device.
Advantages of low energy appliances:
• cost efficiency
• saving energy and resources.

41. P.31 Energy Transfers
Energy cannot be created or destroyed. It can only be
transferred from one type to another.
8 types of energy:
1. Heat
2. Light
3. Sound
4. Electrical
5. Chemical
6. Nuclear potential
7. Potential (Gravitational or elastic)
8. Kinetic
Energy input = Energy output

42. P1.31 Energy Transfers
• Energy transfer diagrams show how energy is
transferred.
• The width of the arrows represents the
amount of energy transferred at each stage.
Example – an old style light bulb.
100J of energy are supplied to the
bulb. 10J are usefully transferred as
light. 90J are transferred as heat.

43. P1.32 Efficiency
Key word:
• Efficiency – the proportion of energy transferred into useful
forms.
Example – a new style light bulb.
100J of energy are supplied to the
bulb. 75J are usefully transferred as
light. 25J are transferred as heat.
= (75 / 100 ) x 100%
= 75%

44. P1.33 Heat Radiation
• Black cars heat up more than other cars
because they absorb more radiation from the
sun.
• Black is the best colour for radiating heat and
absorbing heat.

45. P1.34 The Earth’s temperature
For a system to be at a constant temperature, it
needs to absorb the same amount of power as it
radiates out.