p1 science

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  • Created by: elliesp
  • Created on: 07-05-16 07:37
what can we use infra red for?
in thermograms to detect injury as the body often pumps blood to the injured area to heal it, so this would show up as the warmest area on the thermogram
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why do things heat up?
because they absorb infra red faster than they emit it
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how does infra red travel?
through electromagnetic waves
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what kind of surfaces are best at absorbing infra red? worst?
matt black, shiny light
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what kind os surfaces are best for reflecting infra red? worst?
white light surfaces, matt blakc
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what is the kinetic theory?
it states that all matter is made up of small particles that are constantly moving; the higher the temp, the faster they move. When the particles are close together, they attract each other strongly.
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explain kinetic theory in solids?
in solids, particles are organised in rows and collums and are held together by strong forces of attraction (so they keep a sturdy shape), when the solid is heated the particles vibrate faster and take up more space so the solid expands.
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explain kinetic theory in liquids?
the particles are close, but can move around as the forces of attraction between them aren't strong enough to hold them in a consistent arrangement. This means that the liquid can take on the shape of any container, but the liquid has a fixed volume
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explain kinetic theory in gases?
particles are spread very widely apart & are in a random arrangement, as have virtually no forces of attraction between them (so gases are compressed easily). The particles have a rapid, random motion & fill any space available to them.
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why does a solid expand when it is heated?
when a solid is heated, the particles in it start to vibrate, taking up more space and so expanding the solid.
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explain the process of evaporation?
when a liquid is heated, the particles in it gain energy as they heat up and move around rapidly. Some particles gain enough energy to escape the surface of the liquid & the remaining liquid cools as the particles with the highest energy levels go
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how can you increase the rate of evaporation?
draught (particles move away from surface quickly), larger surface area (more particles escape surface), increase temp (particles gain more energy &move quicker, more escape), reduce humidity (reduce water vap in air, reduce particles falling back in
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explain condensation?
when warm air hits a cold surface it turns into a liquid, as the air particles initially have a lot of energy &move v. far from each other, so as they cool they move around slower & move closer to near particles as the gas condenses into a liquid.
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what is conduction?
particles are tightly packed in a neat arrangement. As the heat source warms up particles in it's area, the particles gain energy &vibrate more rapidly &bump into neighbouring particles, passing on the energy, until all of the solid is heated.
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why are metals good conductors?
they have delocalised electrons which are free to move about the structure and therefore they can transfer their energy very quickly
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what other material contains delocalised electrons?
graphite
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what is an insulator? what makes them good insulators?
an insulator is a material which is bad at conducting, this is because it's atoms aren't arranged neatly in rows and columns so can't pass on energy quickly, and there are no delcoalised electrons which help to pass on energy too.
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what is an example of an insulator?
wood, air, polystyrene
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why is polystyrene sometimes used for ice boxes?
because it's an insulator and will stop heat from the outside being transferred to inside the box, as the heat isn't conducted through tehe material, so the box stays cooler for longer.
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why is air a good insulator?
air is a good insular as the particles are very far apart so the particles can't pass on heat energy via conduction.
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where does convection occur only? why?
gases and liquids, as particles need to move around freely in convection.
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explain the process of convection in a liquid?
particles in heated area gain energy &move around to take up space, so liquid expands.As liquid expands it's less dense &the warmer liquid rises.But water at top is cooler so when warm water meets it, it cools &contracts, becomes more dense & falls
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explain how convection occurs in a boiler system?
particles in boiler gain energy,move quickly,use up space,liquid expands & becomes less dense& rises, transported to storage tank &then from top to where hot water needed. Water cools,contracts,more dense, falls&transported to cold water tap or reuse
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what does the rate of energy transfer depend on?
material object made from, surface area and volume of object, surface the object is on, difference in temp between object and surroundings.
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the faster the rate of heat transfer...
...the faster the temp falls
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How can animals adapt to cold conditions?
thick fur which traps in air which is a good insulator, thick layer of fat which is a good insulator, small surface area so less surface in contact with air = less heat lost, white coat to camouflage selves in snow/
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how can animals adapt to hot conditions?
larger surface area = more surface in contact with air, more heat lost, blood vessels close to skin surface so warm blood can be cooled when exposed to cool air,
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DO VACUUM FLASK DIAGRAM NOW
!!!!!!
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what is a u value? what is the best uvalue for keeping in heat? why?
the rate of heat transfer through a material. Remember, the higher the rate of heat transfer the faster the temp falls...SO the lower the uvalue the better it is at keeping in heat. This is best for homes/buildings.
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what is specific heat capacity?
the amount of energy required to raise 1kg of something by 1 degree.
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what does efficiency tell us?
how much energy an appliance produces that is actually useful
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what is the equation for payback times?
payback time (years) = cost of installation (£) / savings per year (£)
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what are the methods of stopping heat loss in buildings?
draught excluders, cavity wall insulation, roof insulation, double glazing
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how does double glazing prevent heat loss?
between the 2 panes of glass in a double glazing window there is a gap full of air and argon, these are good insulators so reduce heat loss by conduction. Also, as the gap is so small, air can't move around much, reducing heat loss by convection.
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how does cavity wall insulation prevent heat loss?
insulating material is blown into the gap between the brick and the inside wall, so heat loss reduced by conduction. Also, the insulating material stops air circling inside the cavity so reduces heat loss by convection.
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how do draught excluders prevent heat loss?
involves using plastic strips or foam in the gaps in the edges of doors or windows, reducing heat loss by convection.
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how does loft insulation prevent heat loss?
reduces heat loss by conduction a stye insulating material in the roof traps air. Also, as the air is trapped by the insulating material, this stops the air creating a convection current and so heat loss via convection is prevented.
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what does putting metal foil behind a radiator achieve?
metal foil is a good reflector of infra red, so it can reflect some of the infra red back into the room and reduce heat loss via radiation.
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define power?
the rate at which something transfers energy
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what is the order of the national grid process?
power station, step up transformer, pylons, step down transformer , consumer
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what does the step up transformer do?
increases the voltage but reduces the current, as the current has a heating affect, so it is reduced in order to limit the amount of wasted energy.
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what do step down transformers do?
decrease the voltage to make it safe for consumers to use
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what is the advs/disdavs of having underground power lines?
no visual pollution, not a hazard to aircraft, not damaged by weather etc, insulation needed as no air, expensive to lay and to repair as inaccessible
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what is the advs/disadvs of overhead power lines?
layer of insulation already provided by air, quicker to repair, cheaper to install, visual pollution, hazard to air craft, damaged by weather,
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what do normal power stations run on?
coal oil or gas
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how is electricity produced via power stations?
coal,oil or gas burned (chemical energy), which heats water in a boiler and produces steam (thermal energy) which drives turbines (kinetic energy), & then the turbine drive a generator (electrical energy). Steam cools&condenses into water, repeat.
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what are the disadvantages of coal, oil or gas power stations?
non renewable energy resources, global warming, coal and oil release sulfur dioxide when they burn- causing breathing problems for living creatures and contributes to acid rain.
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advs of coal and oil? disadvs?
advs: concentrated source of energy, easy to transport disadvs: co2 released, and sulphur dioxide, oil can be used for other important things
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advs of natural gas? disadvs?
advs: quick to start up and turn off disadvs: co2 released
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what kind of fuel is used in nuclear power stations?
plutonium or uranium
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through what process do nuclear power stations generate heat? what does this mean?
nuclear fission, so the nucleus of atoms in the nuclear fuel split into 2 smaller nuclei, meaning that a lot of energy is released. This creates heat energy, which is used to heat water into steam &the same process as a normal power station occurs.
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what are the advs of nuclear fuel? disadvs?
no polluting gases, produces a lot of electricity BUT v high decommissioning costs , risk of radioactive waste which is health hazard
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what is the order of start up times for the different fuels from longest to shortest?
1) nuclear 2) coal 3) oil 4) natural gas
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which power stations are used to provide a base load of electricity? what does this mean? why?
coal and nuclear as they take the longest to start up so they must run all the time as it is expensive to keep turning their power off and on.
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which power stations are used to provide electricity for peak times?
oil and gas as they have the quickest start up times
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explain hydroelectric power?
water is stored high behind a dam, & contains grav. pot. Water then let through tubes in the dam to go to the other side (kinetic energy), which drives a turbine which powers a generator, converting kinetic energy to electrical.
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advs and disadvs of hydroelectric power
advs: generate a lot of electricity disadvs: flooding which could destroy homes and plant and animal life
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what is pumped storage? when is it used?
pumped stoarge is used when there is a high demand for electricity, it is used in hydroelectric systems where suplus electricity is used to pump water in the lower reservoir back up to the top to be stored as grav pot energy in prep for high demand
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advs and disadvs of pumped storage?
advs: can be switched on quickly to meet peak demands disadvs: can't run continuously
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Explain tidal power? what do smaller systems use?
tides cause water level to rise & fall, turbines built into a barrage across estuary driven by moving water. small systems use submerged generators driven by underwater currents
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advs and disadvs of tidal power?
advs: reliable disadvs: expensive, destroys habitats
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explain wave power?
in an oscillating water column generator, the movement of the waves causes the air to move, which drives turbines and turns a generator.
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advs and disadvs of wave power?
advs: running costs low disadvs: easily destroyed by wave force
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explain geothermal energy?
built near volcanic areas. Cold water pumped into ground and heated up by hot rocks, this produces steam to drive generators and produce electricity.
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advs and disadvs of geothermal energy?
advs: produces a lot of energy disadvs: not practical to extract energy from earth
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what are biofuels? examples?
fuels made from plants. Some examples of biofuels are palm nuts, straw, wood, olives
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what are advs and disadvs to burning biofuels as a power source?
advs: carbon neutral disadvs: large areas of land needed to grow crop
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explain solar cells.
solar cells convert light energy directly into electrical energy
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disadvs and advs of solar cells?
advs: ideal for remote places, solar thermal towers generate a lot of electricity disadvs: not reliable, large areas of solar cells needed to generate a lot of power
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explain turbines.
turbines have blades connected to a housing that contains gears connected to a generator. As the wind blows, the turbine spins, creating kinetic energy which drives the generator and is converted into electrical energy
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advs and disadvs of turbines
advs: running costs are low disadvs: visual and noise pollution, unreliable, dilute energy resource
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what are transverse waves? how are they made?
they are waves that move at right angles to the oscillation, created by an up and down motion
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what are longitudinal waves? how are they made?
waves that are parallel to the oscillation? made from a side to side motion
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what is an oscillation?
vibration
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what is the wavelength?
the distance between the peaks of two waves
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what is the amplitude?
the amplitude is the length of the distance between the midpoint of the wave and it's peak
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how are transverse waves shown? how are longitudinal waves shown?
longitudinal waves are a straight line, whereas transverse waves are up and down (squiggly line)
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what is frequency? what is it measured in?
the number of waves per second, measured in Hz
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what does reflection mean?
to bounce off of a surface
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what is diffraction?
the spreading out of waves through a gap in a barrier.
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how much is the wave diffracted when the gap is small? when the gap is big?
there is a large diffraction when the gap is small, and a small diffraction when the gap is big
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what type of wave is a sound wave?
longitudinal
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why is there no sound in space?
because space is a vacuum and sound waves require a medium to travel through, as sound can only be transferred through particles
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what do oscilloscopes do?
convert longitudinal waves into transverse waves
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what kind of features does a loud sound have?
a big amplitude
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What kind of features does a high pitched sound have?
high frequency
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what are echoes?
echoes are a reflection of sound; they travel through the air until they hit a surface then they bounce back off it.
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what kind of waves are in the electromagnetic spectrum?
transverse
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what are the features of waves in the electromagnetic spectrum?
all transverse waves, all travel at same speed in a vacuum, can be reflected, refracted and diffracted.
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list the electromagnetic spectrum from high freq and low wavelength to low freq and high wavelength
gamma, X-rays,ultraviolet, visible light, infra red, microwaves, radio waves
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what are radio waves used for?
communication, broadcasting
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what are microwaves used for?
cooking, communication
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what is infra red used for?
cooking, tv remotes, security systems (laser lights)
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what is visible light used for?
photography
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what is ultraviolet used for?
fluorescent light
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what are gamma rays used for?
sterilising medical equipment, detection of cancer and it's treatment
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state the different types of energy. What is the analogy you should use to remember them?
SHELPoNK: Sound, Heat, Electrical, Light, Potential, Nuclear, Kinetic
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what is potential energy? what are it's two forms?
gravitational and elastic potential. It is the stored energy of position possessed by an object
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how do you draw a sankey diagram?
the useful energy straight across, the wasted energy down, and the total energy all together at the beginning of the arrow.
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what is the doppler effect?
when a loud object of constant speed moves towards you, the sound waves it produces have a high frequency& short wavelength (creating a high pitch sound), when it moves away they have a low frequency and a long wavelength (making a low pitch sound)
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explain red shift?
if a source of light was moving away from you at a fast speed, the light waves you'd see would have a longer wavelength and decreased frequency. This would make the light look as though it was moving towards the red end of the spectrum.
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what does red shift actually mean in terms of the universe.
Red shift is used to suggest that galaxies are moving away from us, as most of them show up red, this means that they have long wavelengths and are therefore moving away from us, this suggests that the universe is expanding.
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what does the big bang theory suggest?
the big bang theory says that billions of years ago all matter in the universe was condensed into a tiny point, and then started to enlarge massively after a huge explosion, and continues to expand today.
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what is Cosmic microwave background radiation? what does it suggest?
CMBR started as a short length gamma radiation about the same time of the big bang& as the universe expanded, it's wavelength increased& is now detected as microwave radiation, proving that everything is moving away from each other &big bang happened
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How can we summarise the evidence for the big bang provided by CMBR and red shift?
if everything is moving away from each other (proved by increased wavelengths), then they must have all been together at some point in time (i.e, the big bang states all matter was condensed into a tiny point).
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what colour is a light wave with a short wavelength?
it is blue
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Card 2

Front

why do things heat up?

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because they absorb infra red faster than they emit it

Card 3

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how does infra red travel?

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Card 4

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what kind of surfaces are best at absorbing infra red? worst?

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Card 5

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what kind os surfaces are best for reflecting infra red? worst?

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