1. P1: A revision guide
Here’s all you need to know about P1… This may help you with your exam questions  Any questions…ask your Physics teacher

2. Topic 1 Topic 1 Visible light and the Solar System: The Solar System
Refracting Telescope
Reflecting Telescope
Lenses
Waves

3. The Solar System
Geocentric (Earth Centred) Heliocentric (Sun Centred) Ptolemy Copernicus
BUT Galileo discovered 4 of Jupiter’s moons, he disproved Ptolemy completely as not everything orbited Earth!
And the ORBITS are not perfectly spherical, they are elliptical

4. Refraction
Light travels in straight lines. When it enters another material it bends at an interface (boundary). A line at 90o to the interface is called the normal. Changes speed and direction.

5. Refraction in Lenses
Converging lenses (Convex) focus parallel light to a focal point (convergence). The distance between these is the focal length. The fatter the lens the shorter the focal length. Focus light rays to a point, form image on paper, measure the focal length with a ruler.

6. Refraction in Telescopes
The objective lens collects the light and forms an image
The eyepiece lens magnifies the image

7. Real and Virtual Images
A real image is the image formed where the light rays are focussed. A virtual image is one from which the light rays appear to come but don’t actually come from that image like in a mirror.

8. Problems with Refractive Telescopes
Due to light being reflected at boundaries the image that is processed will be fainter
If the star is already feint it will make it harder to detect
Refracting telescopes need to be very long to have a large magnification
Large lenses help magnification but they are heavy and difficult to mould into a perfect shape, this means that the images have distorted colours

9. Reflective Telescope

10. Waves Transfer Energy
TRANSVERSE: Move at right angles to the vibration (Up and Down)
LONGITUDINAL: Move in the same direction as the vibration (Left and Right)

11. Waves FREQUENCY: The number of waves that pass a point in a second
WAVELENGTH

12. Topic 2: The Electromagnetic Spectrum
Beyond the Visible
The EM Spectrum
EM Dangers
Using EM Radiation
Ionising Radiation

13. WAVE SPEED = DISTANCE / TIME
Wave Equations
WAVE SPEED = FREQUENCY X WAVELENGTH (m/s) (Hz) (m)
WAVE SPEED = DISTANCE / TIME
(m/s) (m) (s)
𝑣= 𝑥 𝑡

14. Beyond the Visible Ritter Herschel
Split light with a prism, measured the heat with thermometers. As colours went from violet to red the temperatures increased.
When he placed the thermometer just beyond red it rose again.
He has discovered infrared.
Ritter
Tried to find invisible light beyond the violet. He shone the light onto silver chloride. He found that the silver chloride turned black quicker towards the violet end of the spectrum. It turned black quickest just beyond violet.
He discovered ultraviolet.

15. All Electromagnetic Waves are Transverse
Can travel without any particles to vibrate
In a vacuum they all travel at the speed of light 300,000 km/s
Visible light is made out of all the colours (ROYGBIV)

16. Dangers of EM Radiation
All EM Waves carry energy. At a high frequency this energy is dangerous. Radiowaves- No danger Microwaves- Can internally boil blood Infrared- Surface burns Visible- Can cause temporary blindness UV- Can cause skin cancer X-Rays- Excessive exposure can cause cancer Gamma- Mutates DNA, cancer

17. Uses of EM Radiation
Radio Waves- Communications, satellite, wifi Microwaves- Microwave ovens, mobile phones Infrared- cooking, optical fibres, thermal imaging Visible- human eyes, photography UV- Security markings, disinfectant of water X-Rays- Medical x-rays and airport scanners Gamma- sterilise food and medical equip, detect cancer, treat cancer in radiotherapy

18. Ionising Radiation   γ Type of radiation Symbol What is it made
from?
How far
will it
travel?
What
stops
it?
Alpha
  
Helium
nucleus. 2
protons &
2 neutrons
 cm
Air /paper
Beta
  
High speed
electron m 
Aluminium
Gamma
  γ
High
energy
wave
Lots of m 
Thick lead
&
concrete
Alpha and Beta are not EM waves but they are ionising particles. Like Gamma they can be extremely dangerous as they can mutate DNA in cells

19. Topic 3: Waves and the Universe
Spectrometers
Exploring the Universe
Alien Life?
Life-cycle of stars
Theories of the Universe
Red-shift

20. The Universe is made out of Everything!
Galaxies, planets, stars, nebulae, black holes etc.
Astronomers initially made observations with the naked eye.
Galileo discovered that the Milky Way and some nebulae.
Relative sizes of the universe are hard to imagine you can fit 30 Earths between the Earth and the Moon.
The Sun is over 11,000 ‘Earths’ away.

21. Spectroscopy
The light is split into the visible spectrum. Black lines show up in the spectrum and signify what elements the star was made from. This kind of spectrum actually tells us the types of element present in the outer layers of the sun (they absorb some of the light given out by the core leaving the black lines.)

22. Exploring the Universe
You can use telescopes to detect different wavelengths of the EM spectrum. However we have the problem that some of the spectrum is absorbed by the atmosphere (for safety). Because of this we need to place the telescopes in space so that the wavelengths are not absorbed. DO NOT SAY THAT THE CLOUDS ARE IN THE WAY OR TO BE ‘CLOSER TO THE OBJECT’ 

23. Alien Life
Earth is the only place where we know life exists Water is ESSENTIAL to life. Landers; land on the planet and explore the surface Probes; orbit the planet and photograph the surface Rovers; take close up photographs of the surface We have found other planets orbiting stars but they are too far away to produce a clear image. Search for Extra-terrestrial Intelligence (SETI): Analyse radio waves that have arrived at Earth from Space for a alien message (None have been found so far).

24. Life Cycle of a Star

25. Life Cycle of A Main Sequence Star
1. Life starts in a Nebula (a hot dense of dust & gas) As the cloud gets more dense it starts to collapse under gravity. As the mass gets larger, the gravitational pull does also. This creates a protostar. 2. Eventually the temperatures rise so much that the hydrogen atoms fuse together (fusion) to form helium and release a lot of energy. This star then becomes a main sequence star. 3. This will remain stable for billions of years until the star stops changing hydrogen into helium, the energy source stops and the star begins to collapse in on itself. The outer layers expand causing a red giant. 4. It will remain like this for another billion years before it releases its shell of gas. 5. The rest of the star is forced together under gravity to form a white dwarf. 6. Theoretically it is said that a white dwarf will eventually turn into a black dwarf but no evidence of this has been shown.

26. Life Cycle of a Higher Mass Star
Stars with more mass than the Sun tend to be hotter and burn faster
They fuse Hydrogen into Helium faster to become Super Red Giants.
They will then supernova, where the outer layers rapidly collapse and then explode.
If the star is not that massive the remains will be a neutron star.
If the star is 4x more massive than the sun it will turn into a black hole through gravity. The gravitational pull is so strong that not even light can escape!

27. Red Shift
Towards You
Away From You
BLUE SHIFT: the wavelength is shorter, moving towards you.
RED SHIFT: the wavelength is longer. Moving away from you, if it is more red shift it is moving away faster and is more likely to be further away!

28. Theories of the Universe
Big Bang Theory
Steady State Theory
All of the Universe and matter started out at a singular point of concentrated energy
13.5 billion years ago.
The universe is constantly expanding
The Universe has always been there but is expanding
New matter is constantly created as it expands
Cosmic Microwave Background Radiation(CMB)
Red shift
Redshift

30. Topic 4: Waves and the Earth
Infrasound
Ultrasound
Seismic Waves
Earthquakes
Seismometers

31. Infrasound Any sound below 20Hz is known as Infra-Sound.
The human ear is not sensitive enough to detect either of these two types of wave however many other creatures are.
Infrasound is very useful as it travels very long distances and can be used as a method of communication between animals and a way of detecting Earthquakes and Volcanoes.

32. Ultrasound The ship emits a pulse of ultrasound
Ultrasound is frequencies above 20,000Hz( 20kHz). Some animals such as Dolphins use ultrasound for communication.
Common uses of Ultrasound: Baby scans and SONAR devices.
The ship emits a pulse of ultrasound
This spreads out through the water and some of it hits the sea bed.
A detector on the ship receives the echo and the SONAR equipment detects the time of the two.
We then calculate it using s=d/t
Remember that if you are calculating depth or distance you need to divide it by 2!

33. Ultrasound in Scans
A common use of ultrasound is to make images of babies so that doctors can detect how well the baby is developing
When the scan is made some of the waves are reflected every time they enter a new medium (material).

34. How do plates move?
Convection currents in the magma (hot rises, cool falls).
Friction between plates on the magma
Build up of energy
Energy is released (when they separate) in the form of a seismic wave.

35. P and S waves P or primary waves fastest waves
travel through solids, liquids, or gases
compressional wave, material movement is in the same direction as wave movement
UP and DOWN.
LONITUDINAL
S or secondary waves
slower than P waves
travel through solids only
shear waves - move material perpendicular to wave movement
LEFT to RIGHT
TRANSVERSE

36. How is an Earthquake’s Epicenter Located?
By using seismic wave behavior
P waves arrive first, then S waves
Average speeds for all these waves is known
After an earthquake, the difference in arrival times at a seismograph station can be used to calculate the distance from the seismograph to the epicenter.
You will usually triangulate (use three stations) between other stations, that are different distances away, to calculate the approximate epicenter.

37. Seismic waves tell you about the structure of the Earth as they refract at boundaries with different densities.

38. Topic 5: Generation and Transmission of Electricity
Renewable Resources
Non-Renewable Resources
Generating Electricity
Transmitting Electricity
Paying for Electricity
Reducing Energy Use

39. Renewable Resources Solar Tidal Hydroelectric Wind Geothermal Wave
How they work:
Advantages
Disadvantages
Solar
Solar cells heat air under glass, hot air rises and turns gen
Direct transfer of energy (non-lost)
Have to be in a specific area, only works with light
Tidal
Tides move through a dam turning a turbine
Direct energy transfer
Predictable
Have to have a tide
Not available all year round
Hydroelectric
Falling water in high reservoirs
Available at any time Started and stopped easily
Reservoirs can dry up
Need rainfall to refill them
Wind
Turns a wind turbine directly generating electricity
Need a lot to produce electricity
Dependant on wind
Geothermal
Heat is transferred by hot underground rocks
No harmful gasses
No fuel cost
Need to be by a tectonic plate (location)
Wave
Floating electrical generators. Air forced up pipes, turns a gen
Not predictable
Don’t work in bad weather

40. Non-Renewable Resources
Advantages
Disadvantages
Coal
Formed from fossilised plants
Ready-made fuel.
It is relatively cheap to mine and to convert into energy.
When burned they give off atmospheric pollutants, including greenhouse gases
Oil
A carbon-based liquid formed from fossilised animals.
Gas

41. 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 Generators supply current with alternates in direction (AC)

42. Transmitting Electricity
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

44. P I V P E T POWER The amount of energy transferred in a second.
Power = Current x Voltage
Watts(W) Amps (A) Volts (V) P I V = X
Power = Energy ÷ Time
Watts(W) Joules (J) Seconds (s) P E T = ÷

45. Cost of Electricity 1000W = 1kW
Remember that with this formula you need to identify:
TIME is in HOURS
COST is in PENCE (Unless stated otherwise)
POWER is in KILOWATTS
Cost of 1 hour is in PENCE

46. Payback time= Cost / savings per year
Reducing Energy Use
Payback time= Cost / savings per year
Years Pounds (£)
Cost Efficient means which is the best value for money
Payback time how long it will take to make the money back in relation to savings

47. Topic 6: Energy Transfers
Energy Transfer Diagrams
Sankey Diagrams
Efficiency
Heat Radiation
The Earth’s Temperature

48. Energy Transfers: how the energy is transferred to other forms.
LAW OF CONSERVATION OF ENERGY:
ENERGY IS NEVER CREATED OR DESTROYED, ONLY TRANSFERRED TO OTHER FORMS OR THE SURROUNDINGS
Types of Energy:
Chemical
Elastic Potential
Electrical
Gravitational Potential
Kinetic
Light
Nuclear
Sound
Thermal

49. Energy Transfer Chain for a Torch

50. Conservation of Energy
In physics we use the word system. This is something in which we are studying for changes. They can be very complex (eg, a planet), or quite simple (eg, a piece of metal) If you add up all the energy that has been transferred (Output) and compare it to the energy put in (Input), they should be the same.
OUTPUT ENERGY = INPUT ENERGY

51. Sankey Diagrams:
These show energy conservation, the width of the arrows represents the amount of energy in joules.

52. Efficiency
How good a device is at converting energy into useful forms is know as its efficiency. Low energy light bulbs transfer more of the input electrical energy, into light electricity than older light bulbs which produce excess heat.

53. Efficiency Calculation

54. Heat Radiation
Infrared radiation in the spectrum is heat. ALL objects are continually absorbing and radiating radiation. If an object is hotter than its surroundings it is radiating more heat than it absorbs! COLOURS & TEXTURE: Dark Matte surfaces absorb heat. They also emit more radiation than bright glossy surfaces. Silver reflect nearly all of the heat.

55. The Earth’s Temperature
The Earth theoretically will try to radiate the same amount of energy it is absorbing. HOWEVER Greenhouse gasses trap some of the energy in the atmosphere so not all of it is re-radiated. This leads to (over a long period of time) an increase in the global temperature (global warming).

56. So what happens next…?
There is only a certain amount of heat that additional green house gasses can absorb.
So if the greenhouse gas emissions are stopped that means that the temperature increase will also stop
If greenhouse gasses are removed, the temperature will decrease.
Scientists have came up with the idea of putting huge white screens into space to reflect the sunlight and shade the Earth. Another way is to place thousands of ping pong balls on the sea surface to do the same thing!