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- 1Describe the main features of the geocentric modelThe geocentric model was the idea that the sun, moon, planets and stars all orbited the earth in perfect circles.
- 2Describe the main features of the heliocentric modelThis model is the correct model which states that the earth and all planets orbit the sun which is at the center of the universe.
- 3Explain how Galileo's observations of Jupiter proved the geocentric model wrong.While observing Jupiter Galileo noticed three stars in line, the next day he realised that these stars had moved in the wrong direction of the geocentric model. He realised that these stars were moons orbiting Jupiter which proved that not everything orbited the earth.
- 4How are we able to see stars? How are we able to see planets?They give out visible light - which is why you can see them even though they're far away. Planets reflect sunlight.
- 5Give an example of a transverse wave. Give an example of a longitudinal.Transverse - light + all EM waves. They are S-waves. Ripples on water.
Longitudinal - sound and ultrasound. They are P-waves. A slinky. - 6What is meant by the focal point of a lens?The focal point is where rays hitting the lens parallel to the axis meet.
- 7How many converging lenses does a refracting telescope use?Uses two converging lenses.
- 8Explain how a reflecting telescope works.Uses an objective lens and an eye piece lens. The rays from the object become parallel to the objective lens and converge to form a real image at the focal point. The rays of light from the real image enter the eye piece lens which spreads them out to give a wider angle which will fill more of your eye.
- 9List the 7 types of electromagnetic radiation in order of increasing wavelength.Radio Waves
Microwaves
Infared
Visible Light
Ultra Violet
X-rays
Gamma Rays - 10Which type of electromagnetic radiation has the highest frequency?Gamma Rays
- 11Why are some people worried about the effects of using mobile phones?Mobile phones use microwave radiation and it has cause concern because the object is held close to the brain and there has been the suggested idea of brain tumors but nothing has been proved.
- 12What can too much exposure to UV radiation cause?Can cause sunburn through UV rays in sunlight which can lead to cell mutation and skin cancer. The UV in sunlight can also cause eye damage.
- 13Explain why hilly areas often get poor TV and radio reception.Long wavelengths bend around curved surfaces of earth meaning they don't always reach to hilly areas.
- 14Explain how optical fibres work.Optical fibres uses Infared to transmit data over long distanced as pulses of infared.
- 15List 5 uses of infared radiation around the home.- Used in cooking (grills and toasters)
-Remote controls for TV or DVD
-transmit data between mobile phones or computers.
- Security systems (burglar alarms) - 16What happens when UV light shines on fluorescent material.Fluorescence absorbs UV and emits visible light - which is why fluorescent colours look so bright.
- 17Describe how x-ray imaging can help to find a fracture in someone's bone.x-rays pass easily through flesh but not so easily through bone. Hospitals take x-ray photographs to see if there is any broken bones.
- 18Explain why radiotherapy treatment is directed carefully at only the tumor.High does of gamma rays kill all living cells so they are used to treat cancer. The gamma rays have to be directed carefully and at the right dosage to kill the cancer cells without killing too many of the normal cells.
- 19Give one advantage of irradiating food with gamma rays over other methods of sterilising.Food can be exposed to a high dose of gamma rays which will kill all microbes and keep the food fresh for longer. Better than boiling because it does not involve high temperatures so the food isn't damaged.
- 20Name three types of ionising radiation. What is ionising radiation emitted from?Alpha, Beta, Gamma.
Emitted all the time from all radioactive sources when their nuclei decay. - 21What is a galaxy?A galaxy is a collection of billions of stars.
- 22What does SETI stand for?Search for
Extra
Terrestrial
Intelligence - 23Suggest one type of information a space probe might collect.They collect data and samples such as photographs or soil.
- 24Give two disadvantages of telescopes on earth compared with space telescopes.Space telescopes have a clearer view than those on earth because the earths atmosphere is in the way and absorbs a lot of light coming from space before it can reach us.
There is also pollution. Light pollution makes it hard to pick out dim objects and air pollution can select and absorb light coming from space. - 25Describe the stages of the life cycle of stars.1- Starts of as a nebula, a cloud of dust and gas.
2. The force of gravity makes them spiral together and gravitational energy is converted into heat energy so temperature rises.
3. When the temperature is high enough fusion happens and a star is born which automatically goes into the stable main sequence star stage.
4. Eventually hydrogen runs out and the star swells into a red giant.
5. A small star becomes unstable and becomes a planetary nebula and then a white dwarf.
6. Big stars glow brightly again and explode into a supernova and become a neutron star or a black hole. - 26Explain what red-shift is.Red shift is when we look at light from distant galaxies we find that the frequencies are lower than they should be and so they are shifted towards the red end of the spectrum. Has the same effect with sound as the noise sounds lower-pitched once its moving away from you. Measurements of redshift suggest that galaxies are moving away from us which provides evidence that the universe is expanding.
- 27What is the main theory for the origin of the universe?The Big Bang Theory.
That it started off with a big explosion. - 28What is ultrasound & infrasound.Ultrasound and Infrasound have frequencies above (ultrasound) or below (infrasound) the human range of hearing.
- 29Describe how sonar works.Boats and submarines use sonar to detect stuff in the water around them. They emit rays of ultrasound which reflect of other objects and detect these waves as they arrive back at the boat.
- 30Explain why ultrasound instead of x-rays are used to take images of a foetus.Ultrasound waves can pass through the body and reflect back what is detected. X-rays would be dangerous for the foetus.
- 31What are tectonic plates?The earths surface is made up of tectonic plates. If plates slide they can cause earthquakes.
- 32What are P waves and S waves?They are both types of seismic waves.
P waves - longitudinal and can go through solids and liquids, They are faster than S waves.
S waves - are transverse and can only go through solids. They are slower than P waves. - 33What is the difference between a.c and d.c?a.c - alternating current (keeps changing direction)
d.c - direct current (doesn't change direction) - 34Describe how voltage can be induced using a magnet and a coil of wire.Moving a magnet in a coil of wire induces a voltage because as you move the magnet the magnetic field through the coil changes which induces a voltage and a current flows through the wire.
- 35What is meant by a non renewable energy resource? and name 4.A resource that will run out one day.
-coal
-oil
-natural gas
-nuclear fuels - 36Explain how electricity is generated in a gas fired power station.Most electricity we use is generated from the four non-renewable energy sources in big power stations. The chemical energy is put in a boiler which is turned to heat energy which goes into a turbine and makes kinetic energy which goes in a generator and created electrical energy.
- 37State one advantage and two disadvantages of using renewable energy sources.Advantage - they will never run out
Disadvantages - they are high costs and don't provide as much energy, can also be unpredictable. - 38Explain why a high voltage is used to transmit electricity in the national grid.Because the transmit is huge you need a high current or a high voltage.
With a high current a lot of energy is lost through heat so it is cheaper to have a high voltage.
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- Fichas sobre Sin título, creado por Meg Jackson el 01/05/2015.
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