AQA Physics Unit 1

Frage	Antworten
What is INFRARED RADIATION?	Infrared radiation is a type of electromagnetic radiation, which involves waves rather than particles. This means that, unlike conduction and convection, radiation can even pass through the vacuum of space. This is why we can still feel the heat of the Sun, although it is 150 million km away from the Earth.
Why are matt surfaces good absorbers of heat, but poor emitters?	Because (the colour) black absorbs the heat; it does not reflect it well.
Why are shiny/white surfaces good emitters of heat, but poor absorbers?	Because (the colour) white reflects the heat; it does not absorb it well.
KINETIC THEORY!!! (1/3)	SOLIDS: - They have a fixed shape and cannot flow. - The particles cannot move from place to place. - They cannot be compressed or squashed. - The particles are close together and have no space to move into.
KINETIC THEORY!!! (2/3)	LIQUIDS: - They flow and take the shape of their container. - The particles can move around each other. - They cannot be compressed or squashed. - The particles are close together and have no space to move into.
KINETIC THEORY!!! (3/3)	GASES: - They flow and completely fill their container - The particles can move quickly in all directions - They can be compressed or squashed - The particles are far apart and have space to move into
CONDUCTION!!!	The electrons in piece of metal can leave their atoms and move about in the metal as free electrons. The parts of the metal atoms left behind are now charged metal ions. The ions are packed closely together and they vibrate continually. The hotter the metal, the more kinetic energy these vibrations have. This kinetic energy is transferred from hot parts of the metal to cooler parts by the free electrons. These move through the structure of the metal, colliding with ions as they go.
CONVECTION!!!	Liquids and gases expand when they are heated. This is because the particles in liquids and gases move faster when they are heated than they do when they are cold. As a result, the particles take up more volume. This is because the gap between particles widens, while the particles themselves stay the same size. The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas. The denser cold liquid or gas falls into the warm areas. In this way, convection currents that transfer heat from place to place are set up.
EVAPORATION vs CONDENSATION! GO GO GO!!!	- evaporation involves a liquid changing to a gas. - condensation involves a gas changing to a liquid. Evaporation is the reason why damp clothes dry on a washing line. Condensation is the reason why windows become foggy on a cold day.
Explain the process of EVAPORATION.	The particles in a liquid have different energies. Some will have enough energy to 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 as evaporation happens. This is why sweating cools you down. The sweat absorbs energy from your skin so that it can continue to evaporate.
Explain the process of CONDENSATION.	The particles in a gas have different energies. Some may not have enough energy to remain as separate particles, particularly if the gas is cooled down. They come close together and bonds form between them. Energy is released when this happens. This is why steam touching your skin can cause scalds: not only is the steam hot, but energy is released into your skin as the steam condenses.
Factors affecting the rate of condensation and evaporation:	- the surface area of the liquid is increased. - air is moving over the surface of the liquid.
FINISH THIS SENTENCE: The bigger the difference in temperature between an object and its surroundings, ...	the greater the rate at which heat energy is transferred.
Factors that affect the rate at which an object transfers energy by heating:	- surface area and volume of the object. - material used to make the object. - nature of the surface that the object is touching.
State what is meant by U-VALUE(s).	U-values measure how effective a material is an insulator.
PAYBACK TIME!!! #debt	payback time (years) = cost of installation (£) ÷ savings per year in fuel costs (£)
The double glazing for a house costs £3,000 but saves £150 per year in fuel costs. What is its payback time?	payback time (years) = cost of installation (£) ÷ savings per year in fuel costs (£) = 3,000 ÷ 150 = 20 years
FINISH THIS SENTENCE: Solar panels do not generate electricity, but rather they...	heat up water. They are often located on the roofs of buildings where they can receive heat energy from the sun. This diagram outlines how they work.
ADVANTAGES OF SOLAR PANELS!!!	- solar energy is a renewable energy resource. - no harmful polluting gases are produced.
DISADVANTAGES OF SOLAR PANELS!!!	- solar panels may only produce very hot water in very sunny climates, and in cooler areas may need to be supplemented with a conventional boiler. - although warm water can be produced even on cloudy days, solar panels do not work at night.
What is meant by SPECIFIC HEAT CAPACITY???	The specific heat capacity of a substance is the amount of energy needed to change the temperature of 1 kg of the substance by 1°C (different substances have different specific heat capacities).
SPECIFIC HEAT CAPACITY EQUATION!!! GO GO GO!!! note! You do not need to know these because you have an equation sheet in the exam; you do need to know how to sue them.	E = m × c × θ (- E is the energy transferred in joules, J - m is the mass of the substances in kg - c is the specific heat capacity in J / kg °C - θ (‘theta’) is the temperature change in degrees Celsius, °C).
How much energy is needed to increase the temperature of 500 g of lead from 20ºC to 45ºC? The specific heat capacity of lead is 128 J/kg ºC.	E = m × c × θ mass of lead = 500 ÷ 1000 = 0.5 kg temperature change = 45 – 20 = 25ºC energy needed = 0.5 × 128 × 25 = 1600 J (1.6 kJ)
KCTENLEGS!!!	Kinetic Chemical Thermal Elastic potential Nuclear Light Electricity Gravitational potential Sound
What are SANKEY DIAGRAMS??? (I hate these btw).	Sankey diagrams are diagrams which summarise all the energy transfers taking place in a process. The thicker the line or arrow, the greater the amount of energy involved.
LAW!!!	Energy CANNOT be created or destroyed.
What happens to WASTED energy???	The energy transfer to light energy is the useful transfer. The rest is ‘wasted’: it is eventually transferred to the surroundings, making them warmer. This ‘wasted’ energy eventually becomes so spread out that it becomes less useful.
State what is meant by EFFICIENCY.	The efficiency of a device is the proportion of the energy supplied that is transferred in useful ways.
DECIMAL EFFICIENCY!!! note! You do not need to know these because you have an equation sheet in the exam; you do need to know how to sue them.	efficiency = useful energy out ÷ total energy in
PERCENTAGE EFFICIENCY!!! note! You do not need to know these because you have an equation sheet in the exam; you do need to know how to sue them.	efficiency = (useful energy out ÷ total energy in) × 100
ELECTRICAL ENERGY EQUATION!!! note! You do not need to know these because you have an equation sheet in the exam; you do need to know how to sue them.	E = P × t (- E is the energy transferred in kilowatt-hours, kWh - P is the power in kilowatts, kW - T is the time in hours, h).
TOTAL COST EQUATION!!!	total cost = number of units × cost per unit
FINISH THIS SENTENCE: The fossil fuels are coal, oil and natural gas. They were formed from...	the remains of living organisms millions of years ago and they release heat energy when they are burned. They are non-renewable.
Explain the disadvantages of using fossil fuels.	Fossil fuels are non-renewable energy resources: their supply is limited and they will eventually run out. Fossil fuels do not renew themselves, while fuels such as wood can be renewed endlessly. Coal and oil release sulfur dioxide gas when they burn, which causes breathing problems for living creatures and contributes to acid rain. Fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming. Of the three fossil fuels, for a given amount of energy released, coal produces the most carbon dioxide and natural gas produces the least.
What is CARBON CAPTURE???	Carbon capture and storage is a way to prevent carbon dioxide building up in the atmosphere. It is a rapidly evolving technology that involves separating carbon dioxide from waste gases. The carbon dioxide is then stored underground, for example in old oil fields or gas fields such as those found under the North Sea.
NUCLEAR FUELS!!!	The main nuclear fuels are uranium and plutonium. These are radioactive metals. Nuclear fuels are not burnt to release energy. Instead, nuclear fission reactions (where the nuclei in atoms are split) in the fuels release heat energy. The rest of the process of generating electricity is then identical to the process using fossil fuels. The heat energy is used to boil water. The kinetic energy in the expanding steam spins turbines, which then drive generators to produce electricity.
State the advantage of NUCLEAR FUELS.	Unlike fossil fuels, nuclear fuels do not produce carbon dioxide or sulfur dioxide.
State the disadvantages of NUCLEAR FUELS.	Fossil fuels, nuclear fuels are non-renewable energy resources. If there is an accident, large amounts of radioactive material could be released into the environment. In addition, nuclear waste remains radioactive and is hazardous to health for thousands of years. It must be stored safely.
Advantages of WIND TURBINES:	- Wind is a renewable energy resource and there are no fuel costs. - No harmful polluting gases are produced.
Disadvantages of WIND TURBINES:	- Wind farms are noisy and may spoil the view for people living near them. - The amount of electricity generated depends on the strength of the wind. - If there is no wind, there is no electricity.
WAVE!!!	The water in the sea rises and falls because of waves on the surface. Wave machines use the kinetic energy in this movement to drive electricity generators.
TIDES!!!	Huge amounts of water move in and out of river mouths each day because of the tides. A tidal barrage is a barrier built over a river estuary to make use of the kinetic energy in the moving water. The barrage contains electricity generators, which are driven by the water rushing through tubes in the barrage.
HEP!!!	Like tidal barrages, hydroelectric power (HEP) stations use the kinetic energy in moving water. But the water comes from behind a dam built across a river valley. The water high up behind the dam contains gravitational potential energy. This is transferred to kinetic energy as the water rushes down through tubes inside the dam. The moving water drives electrical generators, which may be built inside the dam.
State the advantages of the previous 3 renewable energy resources.	Water power in its various forms is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced. Tidal barrages and hydroelectric power stations are very reliable and can be easily switched on.
State the disadvantages of the previous 3 renewable energy resources.	It has been difficult to scale up the designs for wave machines to produce large amounts of electricity. Tidal barrages destroy the habitat of estuary species, including wading birds. Hydroelectricity dams flood farmland and push people from their homes. The rotting vegetation underwater releases methane, which is a greenhouse gas.
State the advantages of GEOTHERMAL.	Geothermal energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.
State the disadvantages of GEOTHERMAL.	Most parts of the world do not have suitable areas where geothermal energy can be exploited.
State the advantages of SOLAR ENERGY.	Solar energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced. Solar cells provide electricity in remote locations, such as roadside signs.
State the disadvantages of SOLAR ENERGY.	Solar cells are expensive and inefficient, so the cost of their electricity is high. Solar cells do not work at night.
FINISH THIS SENTENCE: Nuclear power stations and coal-fired power stations usually provide...	'base load' electricity - they are run all the time because they take the longest time to start up. Oil-fired and gas-fired power stations are often used to provide extra electricity at peak times, because they take the least time to start up.
FINISH THIS SENTENCE: The fuel for nuclear power stations is relatively cheap, but...	the power stations themselves are expensive to build. It is also very expensive to dismantle old nuclear power stations and to store their radioactive waste, which is a dangerous health hazard.
RENEWABLE RESOURCES!!!	Renewable resources of fuel do not cost anything, but the equipment used to generate the power may be expensive to build. Certain resources are reliable, including tidal barrages and hydroelectric power. Others are less reliable, including wind and solar energy.
START-UP TIMESSSSSSSS	1.gas-fired station (shortest start-up time) 2. oil-fired station 3. coal-fired station 4. nuclear power station (longest start-up time).
DA NATIONAL GRID #1	Electricity is distributed from power stations to consumers through the National Grid, which allows distant power stations to be used. It also allows a mix of different energy resources to be used efficiently to supply the country’s electricity, whatever the local demand.
DA NATIONAL GRID #2	Electricity is transferred from power stations to consumers through the wires and cables of the National Grid. When a current flows through a wire some energy is lost as heat. The higher the current, the more heat is lost. To reduce these losses, the National Grid transmits electricity at a low current. This needs a high voltage.
What is a TRANSFORMER?	A transformer is an electrical device that changes the voltage of an alternating current (ac) supply, such as the mains electrical supply.
Transformer is needed because they:	- increase the voltage is called a step-up transformer. - decrease the voltage is called a step-down transformer.
FINISH THIS SENTENCE: Power stations produce electricity at 25,000 V. Step-up transformers change the voltage to the very values needed to transmit electricity through the National Grid power lines. Electricity is sent through these at...	400,000 V, 275,000 V or 132,000 V. This reduces energy losses during transmission but the voltages would be dangerous in homes. Step-down transformers are used locally to reduce the voltage to safe levels. The voltage of household electricity is about 230 V.
ELECTRICITY FROM A POWER STATION GOES TO...	1. step-up transformers. 2. high voltage transmission lines. 3. step-down transformers. 4. consumers, (homes, factories, and shops for example).
What are WAVES?	Waves are vibrations that transfer energy from place to place without matter (solid, liquid or gas) being transferred.
Give the correct definition of energy. #sorrynotsorry	Energy is the capacity for doing work.
FINISH THIS SENTENCE: Some waves must travel through a substance. The substance is known as the medium and it can be solid, liquid or...	gas. Sound waves and seismic waves are like this. They must travel through a medium, and it is the medium that vibrates as the waves travel through.
FINISH THIS SENTENCE: Other waves do not need to travel through a substance. They may be able to travel through a medium, but they do not have to. Visible light, infrared rays, microwaves and...	other types of electromagnetic radiation are like this. They can travel through empty space. Electrical and magnetic fields vibrate as the waves travel.

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