P1 Topic 1 & 2 – Cheat Sheets
The Solar System
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Geocentric – The Earth is in the centre
of the solar system and everything
orbits the Earth (discovered by
Ptolemy)
Heliocentric – The Sun is in the centre
of the solar system and everything
orbits the Earth (discovered by
Copernicus and evidence by Galileo)
Refracting telescopes
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Light travels in straight lines – however it can change
direction when it moves into a different material. This is
called refraction.
Refraction happens at the interface (boundary between
two materials e.g. glass and water)
The line at right angles to the interface is called the normal
line.
Refraction in lenses
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Galileo discovered that Jupiter had
moons with orbited Jupiter (this
disproved the Geocentric model)
As telescopes improved more
discoveries where made including the
planets Neptune and Uranus.
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A converging (convex) lens is a glass block that I curved on
both sides to make it thicker in the middle.
The distance between the focus and the lens is called the
focal length.
The focal length can be measured by focusing the image
onto a piece of paper (distance from lens to paper)
Reflecting telescopes
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Reflecting telescopes have a curved
mirror instead of an objective lens so
the colours are not distorted
The Primary mirror focused the light
rays from a distant object to an image
in the same way as an objective lens in
a refracting telescope. This image is
then magnified by the eyepiece lens
(just like a refracting lens)
Reflecting
Refracting telescope
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The convex (objective lens) creates an image inside the
tube and another lens (the eyepiece lens) is used to
magnify this image
Refracting telescopes need to be very long to have large
magnifications.
This lenses are heavy and are difficult to make in a perfect
shape meaning that the images have distorted colours
Waves
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Beyond the visible
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Waves transfer energy
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Transverse waves – particles move at right
angles to the direction that the wave is going
e.g. electromagnetic spectrum
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Longitudinal waves – particles move back and
forth in line with the direction that the wave is
moving. E.g. sound waves
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Seismic waves – caused by explosions or
earthquakes
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Frequency – the number of waves passing a
point in ONE second. Measured in Hertz (Hz)
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Wavelength – the distance from a point on one
wave to the same point on the next wave.
Measured in metres (m)
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Amplitude – The maximum distance of a point
on the wave from its rest position
Herschel put dark coloured filters on his telescope to help
him observe the sun safely
He noticed that different coloured filters heated his
telescope up to different amounts
He used a prism to split sunlight into a spectrum and then
put a thermometer in one of the colours. He placed two
other thermometers either side of the spectrum. Th
temperature rose.
Herschel wondered what would happen if he measured just
beyond the red end of the spectrum, where there was no
visible light.
He had discovered infrared waves (IR)
Ritter found out about Herschel’s work and tried to find
‘invisible rays’ at the other end of the spectrum.
He used silver chloride, a chemical that breaks down to give
a black colour when exposed to light
Ritter showed that silver chloride turned black fastest when
exposed to ‘invisible rays’ just beyond violet. This were
later called Ultraviolet rays (UV)
The Electromagnetic spectrum
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Name
Wave speed (m/s) = distance (m)
Time (s)
Gamma
Wave speed (m/s) = frequency (Hz) x wavelength (m)
EM waves can travel without any particles
They can move through a vacuum
All EM waves travel at 300,000 km/s
These are transverse waves
Wavele Freque Use
ngth
ncy
shortest highest -Sterilising food and
medical equipment
-Detection and
treatment of cancer
X-rays
-Detects broken
bones
UV
-Detecting forged
banknotes
-Security marking
-Photography
-Illumination
Cooking, thermal
imaging, remote
controls
Cooking,
communication
Broadcasting,
communication
Ionising Radiation
Visible
Infrared
Microwaves
Radio
waves
longest
lowest
Danger
-Mutates
cells
which
causes
cancer
-Mutates
cells
which
causes
cancer
-Skin
cancer
Skin
burns
Internal
heating
P1 Topic 3 – Cheat sheets
The Universe
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The Solar System is part of the Milky
way galaxy
Galaxy – a group of millions of stars held
together by gravity
Universe – All the stars, galaxies and space
itself
The moon is the smallest object followed by:
Planets
Sun
Galaxy
Universe
Life-cycles of stars
Nebula – cloud of dust (mainly hydrogen)
Protostar – when a nebula is pulled together by gravity.
Main sequence star – formed when a protostar undergoes
fusion reactions e.g. our Sun
Red giant – main sequence star expands
White dwarf – red giant is pulled together by gravity and it
collapses
Alien Life
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Landers (or space probes) take soil
samples to look for chemical changes
that may have been caused by living
organisms
Electromagnetic radiation that we use
for communication travels into space
and could be detected by alien life.
The Search for Extra-terrestrial
Intelligence (SETI).
Red Shift
Our sun contains helium. We know this
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,
the absorption spectrum is there, but the
pattern of lines has moved towards the red end
of the spectrum, as you can see below.
Spectrum of a distant star
This is called red shift. It is a change in
frequency of the position of the lines.
Theories of the Universe
Big Bang Theory – The theory that says that the Universe began
from a tiny point with huge energy, and has been expanding ever
since.
Evidence – Huge amounts of radiation was released at the beginning
of the Universe this is called cosmic microwave background (CMB)
radiation. The second piece of evidence is the red shift.
This is currently the accepted model for the origin of the Universe
Steady State theory – this theory says that the Universe has always
existed and is expanding. New matter is continuously created within
the Universe as it expands
P1 Topic 4-6 – Cheat Sheets
Infrasound
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Infrasound is a sound with frequencies
less than 20 hertz, Hz
Humans can hear a frequency range
from 20 to 20,000Hz (20kHz)
It can be used for communication
between animals, detection of animals
movement in remote locations and
the detection of volcanic eruptions
and meteors
Ultrasound
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Ultrasound is a sound with frequencies
greater than 20,000 hertz
It can be used for sonar (detect the
depth of the sea), communications
between animals (waves are reflected
by the things around them) and foetal
scanning (waves are reflected and pas
into a different medium)
Non-Renewable Resources
Examples: fossil fuels and nuclear power
Advantages
 More dependable as they do not
depend on the weather – so is
generally available all the time
 Produce cheaper electricity than
renewable sources
Disadvantages
 Non-renewable so will eventually run
out
 Release green-house gases once burnt
(combustion) and can cause acid rain
Seismic Waves
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Created by explosions or earthquakes (detected
using a seismometer)
Longitudinal seismic waves = P waves
Transverse seismic waves = S waves
P waves travel faster than S waves
Renewable Resources
Current – is the flow of charge
Voltage – the amount of energy transferred by the current
Examples: Solar cells, hydroelectricity, wind turbines,
geothermal energy, tidal power and wave power
Advantages
 Renewable so does not run out
 Do not release green-house gases
 Conserve oil supplies
Disadvantages
 E.g. weather dependent so it is not always reliable
 Visual pollution
 Can affect wildlife by destroying habitats
Generating Electricity
Electromagnetic induction – creates a current in a wire
when a wire is moved into a magnetic field
The current can be increased by:
 Using a coil of wire, or putting more turns on the
coil
 Using an iron core inside the coil of wire
 Using stronger magnets
 Moving the wire faster
The direction of the current can be changed by changing the
direction:
 Of the movement of the wire
 Of the magnetic field
Direct current (DC) - current flows in one direction
Alternating current (AC) – current changes direction
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Generators supply current with alternates in
direction (AC)
Transmitting Electricity
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A transformer can change the size of
an alternating current
If the voltage passed through the
nation grid is increased less energy is
wasted as heat and the efficiency is
improved
Power stations convert 25kV to 400kV
before the electricity is sent around
the country
A step up transformer – increases the
voltage and decreases the current.
This happens between power station
and transmission lines to stop heat
being wasted.
A step down transformer – decreases
the voltage and increases the current.
This happens between local
substations and homes to reduce the
voltage for homes
Energy transfers
Conservation of energy – energy is not created
or destroyed it can only be transferred into
another form
Types of energy: thermal (heat) light, electrical,
sound, kinetic (movement), chemical, nuclear
and potential (elastic and gravitational)
Paying for electricity
Power – energy transferred per second (measured in Watts,
W)
Power (W) = energy used (joules, J)
Time (seconds, s)
P=E
T
Power (W) = current (Amps, A) x Voltage (Volts, V)
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Energy in our homes is measured in kilowatt-hours
(kWh)
Cost (p) = power (kW) x time (hours, h) x cost of 1kWh (p/kWh)
Efficiency
Efficiency = useful energy transferred by the device x 100
Total energy supplied to the device