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Physics P1
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- 1What are light, shiny surfaces in relation to infrared radiation?Light, shiny surfaces are poor absorbers, poor emitters but good reflectors of infrared radiation
- 2How does the design of a matte black big stove help improve the rate of energy transfer?A black matte surface is a good emitter of infrared radiation and the stove has a big surface area
- 3What other ways is energy wasted by fire?Producing light
- 4What type of electromagnetic radiation makes the biscuits turn brown in manufacture?Infrared Radiation
- 5Suggest two ways of cooking biscuits in a machine, to make them brownerIncrease the power
Decrease the speed - 6Why are the inside and outside surfaces of the oven light coloured and shiny?Inside surface is a good reflector or poor absorber of IR radiation
Outside surface is a poor emitter of IR radiation - 7Give examples of infrared waves being used for communicationRemote controls
Data transmission
Optical fibre signals - 8What is the equation for wavelengthWave speed (m/s)= Frequency (Hz) x Wavelength (m)
- 9What is a property of infrared radiation that convection and conduction don't have?Infrared radiation involves waves rather than particles, so unlike conduction and convection, radiation can pass through the vacuum of space
- 10Describe different types of surfaces in their relation to infrared radiationDark, matt surfaces are good emitters and absorbers of infrared radiation. Light, shiny surfaces are poor emitters and poor absorbers.
- 11Define conductionThe transfer of heat energy through a material
- 12What are poor conductors of heat called?Poor conductors of heat are called insulators
- 13How do you calculate efficiency?efficiency= useful energy out/total energy in (x100)
- 14Give two environmental advantages of using a wood burning stove rather than heaters that use electricity generated from fossil fuelsWood is renewable, using wood conserves fossil fuels and wood is carbon neutral
- 15What is the equation to calculate the amount of energy required and give the meanings of the unitsE = m x c x θ
E is energy, m is mass, c is specific heat capacity and θ is temperature required - 16An electric motor moves. Give the useful energy output from the motorKinetic energy
- 17What eventually happens to all wasted energy?Dissipates or is lost to the surroundings
- 18Explain how energy is transferred through convection in waterWater particles gain energy and move faster. The particles move apart which causes the water to become less dense so the hot water rises.
- 19By which process does heat energy move through a substance?Conduction
- 20Why does the temperature of the water fall at the fastest rate just after the heater has been switched off?There is a bigger temperature difference between the water and surrounding air so the transfer of energy from the water is fastest
- 21Why is the radiator painted black?Black is a good emitter of infrared radiation. To give maximum rate of energy transfer to the surroudings
- 22How does the number of cooling fins affect the rate of energy transfer from the radiator?The fins increase the surface area, therefore increasing the rate of energy transfer
- 23How does a black metal 'chill mat' with a mesh help increase the rate of energy transfer from a laptopMetal is a good conductor. The mesh has a big surface area and black surfaces are good emitters of infrared radiation
- 24Energy transferred from a hot car engine is used to warm up the air inside the car. What effect does this have on the efficiency of the engine?It increases the efficiency because less input energy is wasted
- 25Explain how conduction works in metalsFree electrons gain kinetic energy and move faster. They diffuse through the metal lattice, transferring energy by colliding with positive ions and other electrons
- 26Define convectionConvection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.
- 27Why are metals good conductors of energy?They contain free electrons. The free electrons at the hot end gain kinetic energy and move faster. They diffuse and collide with other ions and free electrons in the cooler parts, so they transfer kinetic energy to them. So energy is transferred from the hot end to the cool end.
- 28Why are non metals bad conductors of energy?All the electrons are held in the atoms. Energy transfer only takes place because the atoms vibrate and shake each other. This is much less effective than energy transfer by free electrons
- 29Name some good insulators and explain whyMaterials such as wood and fibreglass are the best insulators because they contain air trapped between the fibres. Trapped air is a good insulator
- 30Explain how evaporation helps cool us downParticles with enough energy escape from the liquid and become a gas. The remaining particles in the liquid have a lower average kinetic energy than before, so the liquid cools down. The sweat absorbs energy from your skin so that it can continue to evaporate.
- 31Why does the rate of energy transfer between the inside and outside of the house decrease with timeThe temperature difference between the inside and outside decreases
- 32How does plastic foam between walls reduce energy transfer by convectionAir is trapped in the foam so the air cannot circulate and form a convection current
- 33What is meant by the term U-Value?How effective a material is as an insulator
- 34Explain how high U-Values affect rate of energy transfer through a window compared to a wallThe rate of energy transfer will increase because the glass is not as good an insulator as the wall
- 35Explain convection in terms of particles moving apart/closerParticles gain energy and spread out. Heated fluid is less dense and rises. Particles reach the surface and move along. Particles move closer together, cooler fluid is more dense and sinks. Cooler fluid replaces heated fluid
- 36What factors affect the rate of evaporation?The rate of evaporation increases if the temperature of the liquid increases, the surface area of the liquid increases and if air is moving over the surface of the liquid
- 37What factors affect the rate of condensation?The rate of condensation increases if the temperature of the surface is decreased and surface area is increased
- 38What factors affect the rate at which an object transfers energy by heating?Surface area and volume
The material from which the object is made
The nature of the surface with which the object is in contact - 39Define specific heat capacityThe amount of energy required to change the temperature of 1 kilogram of the substance by 1 degree Celsius
- 40Describe how the plastic cap and glass container of the vacuum flask keeps the liquid inside hotThe plastic cap is a poor conductor and stops convection currents forming at the top of the flask, so stops energy transfer by convection. Glass is a poor conductor so reduces energy transfer by conduction
- 41Describe how the vacuum and silvered surfaces of the vacuum flask keep the liquid inside hotThe vacuum stops energy transfer by conduction and convection because they both require particles. The silvered surfaces reduce energy transfer by radiation because they reflect IR radiation and are poor emitters of IR radiation
- 42How does the size of the ears of an arctic fox help keep the fox warm in a cold environment?The ears have a small surface area so reduce energy radiated by the fox
- 43What is the equation for calculating energy in electricity?E (energy) = P (power) x t (time)
- 44Give on environmental advantage of turning off electrical appliances when they are not being usedConserves fossil fuels
- 45Explain what happens to the particles when a water changes from a gas to a liquidThe kinetic energy of the particles is reduced so they move closer together
- 46If a window is double glazed rather than single glazed, there is less condensation on the inside of the glass. Explain whyDouble glazing provides better insulation. The inside of the glass is not as cold
- 47Why does the air inside a fridge with a freezer compartment form a convection current when the fridge door is closed?The air near the freezer compartment is cooled. Cooler air is more dense so the cooler air falls. The air at the bottom moves upwards
- 48Give one advantage and one disadvantage of replacing an old fridge with a new oneAdvantage: reduces emissions into the atmosphere and costs less to run
Disadvantage: landfill or cost of difficulty of disposal - 49When a person uses the shower, it gets misty. Why?Water evaporates. The mirror surface is cooler than the air which causes condensation on the mirror
- 50What does a high specific heat capacity mean?More energy is required to change the temperature of 1kg of the substance by 1 degree Celsius. It takes longer to heat up because it takes more energy and is useful for storing heat energy
- 51Why does an electrically heated mirror not become misty?The mirror surface is warm so the rate of condensation is reduced
- 52Give some advantages and disadvantages of solar powerAdvantages- Solar power is a renewable source of energy and produces no harmful gases
Disadvantages- Solar panels do not work at night. They only produce very hot water in warm climates and in cooler ones, may need to be supplemented with a boiler - 53How does energy transfer in a non metallic substance take place?Atoms inside the non metal transfer energy because they vibrate
- 54Why is a CHP station more efficient than a coal burning one?Some of the energy that would be wasted by the coal burning station is usefully used to heat homes etc.
- 55What is the national grid?A system of cables and transformers
- 56Using the electricity locally and not transmitting through the national grid increases the efficiency. Explain whyLess energy is wasted
- 57What is the function of a step up transformer?It increases voltage and decreases current which reduces energy transfer to the surroundings from the power cables
- 58Give some examples of energy transfers that everyday electrical appliances useHeating, lighting, making objects move (using an electric motor), and creating sounds and visual images
- 59Which fuels could be used to heat water in power stations?Fossil fuels- burnt to heat water or air
Uranium or plutonium- When energy from nuclear fission is used to heat water
Biofuels- Such as methane and ethanol which can be burned to heat water - 60Which energy sources can be used to drive turbines?Wind, waves, tides and falling water in hydroelectric schemes
- 61What are some advantages and disadvantages of water power?Advantages- renewable, no fuel costs, can be easily switched on and reliable
Disadvantages- Tidal barrages destroy habitats of estuary species, hydroelectricity dams flood farmland and push people from their homes. - 62What is geothermal energy?Energy from hot rocks in the earth
- 63How can a pumped storage hydroelectric system store energy for future use?Water is pumped to a higher reservoir
- 64Name some advantages and disadvantages of solar cells?Advantages- solar energy is a renewable energy source, has not fuel costs and can provide electricity in remote locations, e.g. roadside signs.
Disadvantages- Solar cells are expensive and inefficient, so the cost of their electricity is high. They don't work at night. - 65Why is the output from the power station changed before the electricity is transmitted along the cables of the National Grid?To reduce energy transfer to the surroundings
- 66Give one advantage and one disadvantage of using nuclear power stations rather than gas-fired power stations to generate electricityAdvantage- produces no greenhouse gases/carbon dioxide
Disadvantage- produce long term radioactive waste - 67Why do wind turbines operate at a maximum power output for only 30% of the time?The wind is unreliable
- 68Give one advantage of using underground power cables rather than overheadThey cannot be seen. They are not a risk to low flying aircraft
- 69Give an advantage and disadvantage of small scale production of electricityAdvantage- Small scale production may be useful in some areas, e.g. hydroelectricity in remote areas and solar cells for roadside signs
Disadvantage- It is uneconomic to connect such generation to the National Grid - 70What is meant by a reliable way of generating electricity?Energy is constant and doesn't rely on uncontrollable factors
- 71What does it mean to decommission a nuclear power station?Dismantle and remove radioactive waste/materials
- 72Companies generating electricity could reduce carbon dioxide emissions. Give two ways the companies could do thisReduce the use of fossil fuelled power stations. Use more renewable energy sources
- 73The voltage across the overhead cables of the National Grid needs to be much higher than the output voltage from the power station generators. Explain whyBy increasing the voltage, the current is reduced which reduces the energy loss from the cable and this increases the efficiency of the transmission
- 74One kilogram of a gas has a much larger volume than one kilogram of a solid. Use kinetic theory to explain whyThere are strong forces of
attraction between the particles in a solid which hold the particles close together, but in a gas the forces between the particles are insignificant so the particles spread out - 75The temperature of the liquid in container decreases as the liquid evaporates. Use kinetic theory to explain whyParticles with the most energy leave the liquid surface. So the average energy of the remaining particles decreases, and the lower the average energy of the particles, the lower the temperature of the liquid
- 76Define carbon captureTo prevent carbon dioxide building up in the atmosphere, we catch it and store it. Some of the best natural containers are oil and gas fields, such as those under the North Sea
- 77Why do we increase the voltage for a given power?Increasing the voltage reduces the current required to transfer the same amount of power and this reduces the energy losses in the cables
- 78What is the voltage of household electricity?230V
- 79How does electricity from the power station reach the consumer?It goes from step up transformers, high voltage transmission lines, step down transformers and then to consumers
- 80How do oscillations move in transverse wavesOscillations are perpendicular to the direction of energy transfer
- 81How do oscillations move in longitudinal waves?Oscillations are parallel to the direction of energy transfer
- 82What type of waves are electromagnetic, sound and mechanical waves?Electromagnetic waves are transverse, sound waves and longitudinal and mechanical waves may be either transverse or longitudinal
- 83What order do the electromagnetic waves go in the spectrum from shortest to longest wavelengthGamma rays
X rays
Ultraviolet
Visible light
Infrared
Microwaves
Radio waves - 84How do sounds waves differ from other waves?Sounds waves must travel through a substance called the medium and it is the medium that vibrates when waves pass through. Other electromagnetic radiation travels through empty space
- 85Which waves show areas of rarefraction and compression and explain what this meansLongitudinal waves. Compression is where the parts of the spring are close together and rarefraction is where they are far apart
- 86What is the range of the electromagnetic spectrum?10 to the minus 15 - 10 to the 4
- 87Define amplitude, wavelength and frequencyWavelength- Distance from one peak to the next
Amplitude- The maximum displacement from the equilibrium position
Frequency- The number of waves passing a point per second (Hertz) - 88What is the equation for wavelength?Wave speed(m/s) = Frequency(Hz) x Wavelength(metres)
- 89Give two properties that are the same for radiowaves and microwavesThey are both transverse and both can be reflected/refracted/diffracted/absorbed
- 90What is the property of microwaves that allows them to be used for satellite communications?They can pass through the ionosphere
- 91Why is it possible to receive radio signals but not terrestrial television signals?There is diffraction of waves around hills. Wavelength needs to be a similar size to the gap. Radio has a long enough wavelength
- 92What does a frequency of 440Hz mean?440 sounds waves produced in one second
- 93Describe how switching a desk lamp on and off shows that light waves transfer energyLight off- no rotation
Light on- faster rotation - 94What is a virtual image?An image which cannot be projected onto a screen
- 95Define refractionSounds and light waves change speed when they pass across the boundary between two transparent substances with different densities, e.g. air and glass. This causes them to change direction; refraction
- 96How can radio waves, microwaves, infrared and visible light be used for communication?Radio waves- television and radio
Microwaves- mobile phones and satellite television
Infrared- remote controls
Visible light- photography - 97What is the normal and its relevance to refraction?The normal is a construction line perpendicular to the mirror at the point of incidence. Refraction doesn't happen if the waves cross the boundary at an angle of 90° (the normal). Instead they carry straight on
- 98What does the law of reflection state?The angle of incidence equals the angle of reflection
- 99Give examples of longitudinal and transverse wavesElectromagnetic spectrum- transverse
Sounds waves- longitudinal. They cause vibrations in a medium - 100What determines pitch and loudness?Pitch is determined by its frequency and loudness by its amplitude
- 101Why is the image seen by the student virtual?The image is formed by virtual rays crossing
- 102Why is it better for the environment if people switch off their televisions, instead of leaving them in stand by mode?TVs in stand by use electricity which is generated by burning fossil fuels which contributes to global warming
- 103Changing from using halogen bulbs to LED bulbs would reduce the cost of running the growth cabinet. Explain whyThe input power would be less so it produces less waste energy. The waste energy increases temperature of the cabinet so the cooler is on for less time
- 104Explain one effect that burning fossil fuels has on the environmentProduces carbon dioxide that contributes to global warming
- 105What is the importance of a short start up timeIt can meet surges in demand
- 106Give another advantage of a pumped storage hydroelectric power stationIt stores energy for later use
- 107Some opponents of wind turbines think an increase in wind turbines will lead to fluctuations in electricity supplies. Explain whyTurbines do not generate at a constant rate
- 108Between 2002-2008 electricity being used in the UK decreased. Explain whyMore people became environmentally aware
- 109Describe how electricity is generated in a hydroelectric power stationWater moves from a higher level to a lower level, transferring GPE to KE, rotating a turbine to drive a generator, transferring KE to electrical energy
- 110The increasing use of energy resources to generate electricity within developed countries has ethical implications. Suggest one ethical implicationUnequal use of energy resources
Fair access to energy for all - 111Which type of electromagnetic radiation has the shortest wavelength?Gamma rays
- 112State one difference between an ultraviolet and visible light rayUltraviolet has a higher frequency
- 113Describe the angle of refraction in relation to the angle of incidence as light rays refract when travelling from air to glassWhen a light ray refracts as it travels from air into glass, the angle of refraction is less than the angle of incidence
When a light ray refracts as it travels from glass into air, the angle of refraction is more than the angle of incidence - 114What does red shift tell scientists about the direction most galaxies are moving?They are moving away from each other
- 115What information can scientists find out about a galaxy when they measure the size of the red-shift the galaxy produces?The distance from the Earth
The speed the galaxy is moving - 116What does the observation of red shift suggest is happening to the universe?The universe is expanding
- 117How does the red-shift from distant galaxies provide evidence for the beginning of the Universe?Red shift shows galaxies are moving away from each other, more distant galaxies show bigger red shift. Suggests single point of origin of the universe
- 118What do scientists believe is the origin of CMBRRadiation produced after the big bang
- 119Why was the discovery of CMBR so important to the scientists believing the Big Bang theory to be correct?It can only be explained by the 'Big Bang'
- 120How is the wavelength of CMBR expected to change over the next billion years?It will increase as the universe continues to accelerate outwards
- 121Many scientists think the big bang theory explains....The origin of the universe
- 122The discovery of CMBR was important because?It provided more evidence to support the Big Bang theory
- 123Scientists have concluded that the two stars in a binary star system orbit around a fixed point between the two stars. A comparison of the spectra from the two stars in a binary star system provides evidence to support this conclusionStar A is moving away from Earth, whilst Star B shows a decrease in wavelength, so is moving closer to Earth
- 124Define the Doppler effectIf a wave source (light, sound or microwaves) is moving relative to an observer there will be a change in the observed wavelength and frequency. Moving away- wavelength increases and frequency decreases
- 125What is the Big Bang theory and CMBR?The Big Bang theory states that the universe began from a small initial point. CMBR is a form of electromagnetic radiation filling the universe
- 126What effect do sounds waves have on pitch?As the source moves closer, the sounds become compressed and the pitch increases. As it moves away, the sound waves stretch and the pitch decreases
- 127Why can a receiver only pick up a signal if a satellite is usedBecause the Earth is curved
- 128Why are microwaves used to send signals rather than radio waves or visible light?Microwaves are reflected by the ionosphere and clouds and cannot pass through the atmosphere. Visible light would scatter because of the particles in the air
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- Fichas sobre Physics P1, creado por iazahussain el 30/11/2015.
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