P1Lenses

Ray Diagrams

Reflecting and Refracting Telescopes

SETISETI is the Search for Extra Terrestrial Intelligence. They look for interesting radio signals from other planets.

Hubble TelescopeThe Hubble telescope was sent into space to ovoid dust and light pollution. It can see a billion times clearer than what can be seen unaided on earth.

Types of TelescopeOptical telescope- Optical telescopes use visible light to observe the 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.

Life cycle of stars

The life cycle of our sun

Red shiftAs 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 universe is always expanding.

CMB RadiationCosmic Microwave background radiation comes from all parts of the universe. As the universe expands, the CMB radiation drops in frequency. This helps to support the big bang theory.

InfrasoundA longitudinal wave with a frequency below 20H2

Uses of infrasoundAnimal: animals such as elephants use infrasound to communicate over long distances

Meteor and volcano detection: Meteors and volcanos produce infrasound. This can be detected in order to prevent it from causing harm.

UltrasoundA longitudinal wave with a frequency above 20,000H2

Uses of UltrasoundPre-natal scans: Ultrasound can pass through the body. When it reaches something different (e.g. the baby) the wave is sent back. A computer analysis the exact timing of these waves and creates an image.

Sonar: Things such as submarines use sonar. A wave is sent out. When it hits an object, the wave bounces back and registers on a computer that there is something there.

The earths structure

Radioactive decay in the mantle produces heat. This causes the mantle to move in convection currents.

The crust and 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 structure of 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 wave to travel off in another direction. This helps scientists to work out where each section of the earth is.

SeismographsSeismographs can be used to find the epicentre of an earthquake. The distance from the earth quake and the seismograph can be calculated. If you have 3 seismographs, the epicentre can be worked out through triangulation.

Electrical Power Electrical Power is the amount of energy transferred per second

How to calculate powerP- Watts

I- Amps

V- Voltage

How Can a Magnet and a Coil Produce a CurrentWhen a magnet moves over a coil, a current is produced. To do this, many power stations use turbines to spin the magnet. This also produces a current. To turn the magnet, fossil fuels are burnt in order to heat water that will produce steam which will then turn the turbine. This method always produces an A.C current.

How different factors affect electromagnetic induction

A.C Vs D.CA.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 expensive to put lots of D.C generators in a small area

Renewable energyHydroelectricityA 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 powerWave power generates electricity from the up and down motion of waves.

Tidal EnergyThe sun and the moon cause water levels to build up behind a barrages. The water is then released. This turns a turbine as it passes through.

Wind powerWind causes a wind turbine to turn. This generates electricity

Solar CellsConverts sunlight into an electrical current

Geothermal EnergyCold water is pumped down under ground. Hot rocks return this water as steam. This steam can be used to turn a turbine in order to produce electricity

Burning BiomassBiomass is waste such as animal droppings and landfill rubbish. This can produce heat to power generators. This is carbon neutral as the plants burnt take in CO2 and release it when burnt.

The National GridTransformers-

Energy can be saved in your house

Loft insulation Hot water tank jacket Double glazing Draught proofing Thick curtains Cavity walls insulation

Cost of electricityUnits (kWh) = power (kW) × time (h) … so …

Total cost = power (kW) × time (h) × cost per unit

Types of Energy

Efficiency EquationEfficiency = useful energy output ÷ useful energy input

So…

90 ÷ 100 = 0.9

Heat Radiation

Surfaces that are black absorb radiation and then reemits it.

Silver surfaces reflect radiation.

Objects with a constant temperature…