This document discusses various topics related to physics including: 1) Different types of telescopes like optical, radio, and x-ray telescopes and how they observe different parts of space. 2) The life cycle of stars and how stars like our sun are formed and evolve over time. 3) Red shift phenomenon which provides evidence that the universe is expanding as galaxies move further away from us. 4) Different types of waves like infrasound, ultrasound, seismic waves and how they are used to detect volcanoes, do pre-natal scans, and examine the inner structure of the Earth.

1. P1
Lenses
Ray Diagrams
Reflecting and Refracting Telescopes

2. SETI
SETI is the Search for Extra TerrestrialIntelligence. They look for interesting
radio signals fromother planets.
Hubble Telescope
The Hubble telescope was sent into spaceto ovoid dust and light pollution. It
can see a billion times clearer than what can be seen unaided on earth.
Types of Telescope
Optical telescope-
Optical telescopes use visiblelight to observethe solar system
Radio telescope-
Radio waves are emitted by stars and planets. The radio telescope can pick
these signals up and a computer then coverts that signal into an image.
X-ray telescope-
X-ray telescopes can pick up heat from space(e.g. exploding stars).
How is a wave refracted at a boundary
How to calculate wave speed
 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.

3. Life cycle of stars
The life cycle of our sun

4. Red shift
As something moves further
away the wavelength starts to
move towards the red end of
the spectrum. When scientists
observed other galaxies they noticed they were moving further away. This
gives evidence that that universeis always expanding.
CMB Radiation
Cosmic Microwavebackground radiation comes fromall parts of the universe.
As the universeexpands, the CMB radiation drops in frequency. This helps to
supportthe big bang theory.
Infrasound
A longitudinal wave with a frequency below 20H2
Uses of infrasound
Animal:animals such as elephants useinfrasound to communicate over long
distances
Meteor andvolcano detection: Meteors and volcanos produceinfrasound.
This can be detected in order to prevent it fromcausing harm.
Ultrasound
A longitudinal wave with a frequency above20,000H2
Uses of Ultrasound
Pre-natal scans: Ultrasound can pass through the body. When it reaches
something different(e.g. the baby) the waveis sent back. A computer analysis
the exact timing of these waves and creates an image.
Sonar: Things such as submarines usesonar. A waveis sent out. When it hits
an object, the wavebounces back and registers on a computer that there is
something there.

5. The earths structure
Radioactive decay in the mantle produces heat. This causes the mantle to
move in convection currents.
The crustand the upper part of the mantle are broken up into tectonic plates.
These tectonic plates can hit together at plate boundaries. This can cause
earthquakes.
Seismic waves
Seismic waves can be used to look at the structureof the
earth. When seismic waves travel through one part of the
earth, it flows evenly. When the seismic waves hits a
different part of the earth it kinks, causing the waveto travel
off in another direction. This helps scientists to work out
whereeach section of the earth is.
Seismographs
Seismographs can be used to find the epicentre of an
earthquake. The distancefrom the earth quake and
the seismograph can be calculated. If you have 3
seismographs, theepicentre can be worked out
through triangulation.

6. Electrical Power
Electrical Power is the amount of energy transferred per second
How to calculate power
P- Watts
I- Amps
V- Voltage
How Can a Magnet and a Coil Produce a Current
When a magnet moves over a coil, a currentis produced. To do this, many
power stations use turbines to spin the magnet. This also produces a current.
To turn the magnet, fossilfuels are burntin order to heat water that will
producesteam which will then turn the turbine. This method always produces
an A.C current.
How different factors affect electromagnetic induction
A.C Vs D.C
A.C = Alternating Current -
 Electrons can move in any direction
 Less loss of energy through the wire. This means less
generators are needed
D.C = Direct Current -
 pushes electrons in one direction around a circuit
 Energy is lost as it passes through the wire. This means that
it is expensiveto put lots of D.Cgenerators in a small area

7. Renewable energy
Hydroelectricity
A big dam is built. Water builds up behind the dam. Small amounts of water is
let through at a time. This water can be used to turn a turbine to create power
Wave power
Wave power generates electricity fromthe up and down motion of waves.
Tidal Energy
The sun and the moon causewater levels to build up behind a barrages. The
water is then released. This turns a turbine as it passes through.
Wind power
Wind causes a wind turbine to turn. This generates electricity
Solar Cells
Converts sunlightinto an electrical current
Geothermal Energy
Cold water is pumped down under ground. Hotrocks return this water as
steam. This steam can be used to turn a turbine in order to produceelectricity
Burning Biomass
Biomass is wastesuch as animal droppings and landfill rubbish. This can
produceheat to power generators. This is carbon neutral as the plants burnt
take in CO2 and release it when burnt.
The NationalGrid
Transformers-
Energy can be saved in your house
 Loft insulation
 Hot water tank jacket
 Double glazing
 Draughtproofing
 Thick curtains
 Cavity walls insulation

8. Cost of electricity
Units (kWh) = power (kW) × time (h) … so …
Total cost = power (kW) × time (h) × cost per unit
Types of Energy
Efficiency Equation
Efficiency = useful energy output ÷ usefulenergy input
So…
90 ÷ 100 = 0.9
Heat Radiation
Surfaces that are black absorb radiation and then reemits it.
Silver surfaces reflectradiation.
Objects with a constant
temperature…