2. They become more dense 3. So the air falls 4. The warmer air at the bottom is displaced/moves upwards Water Heater

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1 Infrared Radiation All objects emit and absorb infrared radiation. The hotter the object the more infrared radiation is given off. Dark, matt surfaces are good absorbers and emitters of infrared. Light, shiny surfaces are bad absorbers and emitters Light shiny surfaces are good reflectors of infrared radiation Radiation does not need particles to travel. It can pass through a vacuum such as through space or through double glazing. Kinetic Theory: Solid: Particles close together No room for particles to move closer Particles vibrate about a fixed point Least amount of energy Strong forces of attraction between the particles Liquid: Particles close together No room for particles to move closer Particles can move around Gas: Particles far apart Space between the particles so they can be compressed Move randomly No force of attraction between the particles Evaporation & Condensation: Evaporation is when a liquid is heated and it turns into a gas. To increase evaporation increase the: Temperature Wind speed Surface area Condensation is when a gas turns into a liquid because it has lost energy. The energy is red to the surroundings. Convection: Convection s heat in liquids and gases (fluids). A common example is in a fridge or a water heater. Fridge 1. Air particles next to the freezer compartment cool/lose energy 2. They become more dense 3. So the air falls 4. The warmer air at the bottom is displaced/moves upwards Water Heater 1. Water particles next to the heater gain energy 2. The particles spread out 3. And become less dense 4. So the warm particles rise. Conduction: Conduction s heat in a solid. The particles vibrate more when heated and this causes them to collide with the particles next to them, ring the heat. HT Free electrons in a conductor move through a structure and collide with atoms to energy quicker. Rate of heat : The rate at which an object s energy by heating depends on: surface area - larger surface area means faster The material from which the object is made conductors heat faster The surface of which the object is in contact with. The bigger the temperature difference between an object and its surroundings, the faster the rate at which energy is red by heating. How does the flask s design prevent heat loss? 1. Plastic cap prevents heat loss via conduction because plastic is an insulator. 2. The vacuum prevents heat loss conduction and convection because there are no particles. 3. The silver surface prevents heat loss by radiation because the surface reflects the radiation back into the flask. It is also a poor emitter of infrared radiation. 4. Glass is a poor conductor so the glass prevents heat loss via conduction. Heating and insulating buildings: U-values measure how effective a material is as an insulator. The lower the U-value, the better the material is as an insulator. Using a material with a low U-value will prevent heat loss. Materials with a low U-value are used in housing insulation. Solar panels may contain water that is heated by radiation from the sun. they use copper pipes because they conduct heat. This hot water can then be used to heat buildings or provide hot water from a tap. Specific Heat Capacity: The specific heat capacity of a substance is the amount of energy required to change the temperature of 1kg of the substance by one degree Celsius. E = m x c x θ E is energy red in joules, J m is mass in kilograms, kg θ is temperature change in degrees Celsius, C c is specific heat capacity in J / kg C

2 Energy s and efficiency: Energy comes in many forms, for instance: Gravitational Potential Energy (energy due to a position above the ground) - water behind a hydroelectric dam has this. When it falls it is red to. Kinetic Energy: energy of movement. Chemical Energy: this is stored in fuel, red to heat and light when they are burned. Light Energy given our by light bulbs. Heat Energy this is always produced during energy s, thanks to friction, and is usually wasted (unless it is a heater!). Energy can only be red, stored or dissipated. It CANNOT be created or destroyed. When energy is red only part of it is red usefully, the rest is wasted. For example: A light bulb has an input of electrical energy. The output is both light and heat. Light energy is what we want, so is useful. Heat is not what we want from a light bulb, so this is wasted. Wasted energy is red to the surroundings and causes the surroundings to become warmer. It spreads out so it isn t useful any more. The amount of energy that we get out of an object that is useful is determined by how efficient the object is. To calculate the efficiency of a device use one of the following: Usefulness of electrical appliances: You need to be able to describe the energy s that happen in different devices/appliances and say whether the energy output is useful or wasted. Remember useful is what you want and wasted is what you don t want. An example of an energy is the one to the left of a light bulb. This can also be represented using a Sankey diagram. The start of the arrow shows total energy in, the arrow the carries on to the right shows the useful output energy and the one that points down shows the wasted output energy. There are no devices that can all the input into useful output, so nothing is 100% efficient. The efficiency of this bulb = = 0.75 or 75% (if I am asked for a percentage) Low energy bulbs (like LED lights) are more efficient, so they reduce energy consumption and save you money. Transferring electrical energy: The amount of energy an appliance s depends on how long the appliance has been switched on for and the power of the appliance. The longer it is on the more energy it s. The higher the power, the more energy it s. To calculate the amount of energy red the following equation can be used: E is the amount of energy red (in J or kwh) P is the power (in W or kw) t is the time (in s or h) Remember 1kW is the same as 1000W Remember 1 minute is the same as 60 seconds Remember 1 hour is the same as 3600 seconds. You also need to be able to calculate the cost of mains electricity given the cost per kilowatt-hour. You need to multiply the amount of energy used (kwh) by the cost for 1 kwh. An equation for this is not given. E.g. A TV is on for 5 hours. It has a rating of 1.2kW. E = P x t = 1.2 x 5 = 6 kwh If the cost of electricity is 13 pence per unit. The cost of running the TV is 6 x 13 = 78p If you get a more efficient TV, that cost goes down. However, like doing anything reduce your energy costs, it costs money to get the new TV (or put in double glazing etc.) The time it takes to get the money back in savings on bills is called the payback time. Divide the cost of the thing (like the new TV) by the saving per year to get the payback time in years.

3 Power Stations To generate electricity in power stations we Heat water to produce steam The steam turns the turbine The turbine turns the generator The generator produces electricity which is sent to the national grid. To heat the water to produce steam we need to burn a fuel. The energy sources for this include: Fossil fuels (Coal, oil and gas) which are burned to heat water. They produce carbon dioxide which causes global warming. Uranium and plutonium are nuclear fuels. When they do a process called nuclear fission energy is released which heats water to generate steam. Biofuels (such as wood) can be burned to heat water and produce steam. Start up times: power stations take time to get up and running and start producing electricity. Gas power stations have the shortest start up times so they are used when electricity is in high demand. of Overhead 1. Doesn't need a cooling system 2. Easy to repair of Overhead 1. Visual pollution 2. Increases rick of electric shock 3. Affected by the weather of Underground 1. No a danger to low flying aircraft 2. Less chance of electric shock of Underground 1. Requires a cooling system 2. More difficult to repair Energy Sources: Energy sources can be split into two types: : They are constantly replenished and will not run out. Non- : The supply is limited and will eventually run out. Non- Resources Non renewable resources include: coal, oil, gas and nuclear fuels. of using fossil fuels Relatively cheap and easy to obtain Most power stations are already designed to use them of using fossil fuels Non-renewable Release sulfur dioxide gas when they burn, which causes acid rain Release carbon dioxide when they burn, which increases global warming. Carbon capture and storage can be used to prevent carbon dioxide building up in the atmosphere. It is rapidly evolving and the carbon dioxide can be stored underground. of nuclear Do not produce carbon dioxide or sulphur dioxide. Produces a lot more energy than fossil fuels of nuclear Non-renewable Radioactive material can be released into the environment Nuclear waste remains radioactive and is hazardous to health for thousands of years, so it must be stored safely. When finished nuclear plants are decommissioned which can be expensive. The National Grid: Electricity is distributed from power stations to houses by the national grid. The National Grid Contains: transformers, cables and pylons. To reduce the amount of energy loss from the cables we increase the voltage to reduce the current. Step-up transformers increase the voltage, step-down decrease the voltage. Overhead or underground cables can be used to electricity : resources can be used to generate electricity. Biomass: burning plant matter (eg wood) Carbon Neutral Hydroelectric: when water is pumped upwards and fall back down over a turbine Very reliable No carbon dioxide produced Geothermal: in volcanic areas, water is pumped below ground where there are hot rocks which produces steam to turn the turbine. Wind: using wind to directly turn the turbine No carbon dioxide produced Plant growth is unreliable Plant should be used for food Can cause localised flooding Can disturb fish populations Only available in volcanic areas with hot rocks Only provides electricity when it is windy Solar: using the suns radiation to heat water Only works when it is sunny

4 Waves: All waves energy from one point to another. They are split into two types: Transverse Examples of these waves are any of the electromagnetic waves such as infrared, X-ray etc. Oscillations are perpendicular to the direction of energy The wavelength is the distance from one peak to the next. Always be specific when drawing this. The longer the wavelength the lower the sound. The amplitude is the height of the wave from the middle. This tells us how loud the sound is. Longitudinal The one example of this wave is the sound wave. Oscillations are parallel to the direction of energy When the wavelength gets smaller that is called a compression. When the wavelength gets longer that is called a rarefraction. Frequency is the amount of waves that pass a point in a second. All waves obey the wave equation: v is the speed of the wave, m/s f is the frequency of the wave, Hz Λ is the wavelength, m Electromagnetic Waves: The electromagnetic spectrum is a continuous spectrum of waves. You need to know the order as shown below. Radio waves have the longest wavelength of 104 meters. They have the least energy. Gamma rays have the shortest wavelength of meters. They have the most energy. All electromagnetic waves travel at the same speed in a vacuum. Communication: Radio waves used in radios and TV Visible light - used in photography Infrared used in remote controls Reflection, refraction & diffraction: All waves can be reflected, refracted and diffracted. Refraction is where waves change direction/bend because they change the material they are travelling through. They bend due to a change in speed. Waves are not refracted if they travel along the normal. Diffraction is when the waves spread out after passing through a gap. The gap must be the same size as the wavelength otherwise they will not be diffracted. Reflection is where waves reflect off a surface. The angle of incidence is equal to the angle of reflection. Sound: Longitudinal waves They cause vibrations in the substance that they are travelling through and these are what we detect. Sound can not travel through a vacuum because there are no particles to vibrate. Humans can hear sound from 20Hz to 20,000Hz. The pitch of a sound is determined by its frequency. High frequency means high pitch. How loud a sound is determined by the amplitude. Large amplitude means a loud sound. Red-shift: Doppler Effect: if a wave source (light, sound or microwave) is moving towards or away from you the frequency of the wave will change. Red Shift: If a wave is moving away from you the wavelength will increase (and the frequency will decrease). The further away a galaxy the faster it is moving and therefore the greater the red shift. This gives evidence that the universe is expanding. Big bang Theory: The theory that the universe originated from a single tiny initial point. Cosmic microwave background radiation (CMBR): is a form of EM radiation that fills the universe. It was present just after the universe was formed. The Big Bang Theory is currently the only theory that can explain its existence.

5 Data In science lessons, and therefore in exams, you are often questioned about data and maths stuff. Here is some information to help you. Averages 2,2,2,3,5,6,7 Mode the most common. From the numbers above it would be 2 Median the one in the middle. From the numbers above it would be 3 Mean add them all up and divide by how many you have. Frome the numbers above it would be 3.9 (you could round this to four. Anomalies 2,2,2,3,5,6,15 This is a piece of data which does not fit the pattern as seen on the graph. In the numbers above the anomalies is the number 15. To calculate the mean you would miss out the anomalous result therefore only adding the 2,2,2,3,5,6 and divide by 6. Variables Independent what you change Dependent what you measure Control what you keep the same. A common question usually goes like this: Q In the investigation we did not get the results we expected. What could have caused these errors. The answer is usually measuring errors such as: Measured the time incorrectly Measured the mass incorrectly Measure temperature incorrectly Measured the volume of gas incorrectly Just read the question thoroughly and figure out what could have been measured incorrectly. Continuous Vs Categoric Data A set of results can be displayed on a graph the type of graph used depends on the type of data. Continuous if both the variables are continuous data use a line graph/scatter graph. Continuous means can take any value eg weight, height, shoe length etc. Categoric if one of the variables is categoric data use a bar chart. Categoric means will fit into a category such as blood group, eye colour, gender. Describing and Explaining Graphs Describing graphs means to say what you see. You do not have to use the word because you are not explaining what is happening. Always quote data. Between 0 and 4 light intensity units, as light intensity increases the rate of photosynthesis increases rapidly. Between 4 and 12 light intensity units, as light intensity increases rate of reaction increases more slowly. Between 12 and 16 light intensity units the graph levels off and the rate of photosynthesis no longer increases. Explaining graphs means telling the examiner why. Between 0 and 12 light intensity units the rate of reaction increases because there is more energy for photosynthesis to occur. Between 12 and 16 light intensity units the rate of reaction levels off because there is another limiting factor such as the amount of carbon dioxide.