Heat is a type of and is therefore measured in (J). Temperature is a measure of how much energy an object has. It is measured in degrees ( C).

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1 Lesson 1: Revision of S2 Heat Heat and Temperature Heat is a type of and is therefore measured in (J). Temperature is a measure of how much energy an object has. It is measured in degrees ( C). Heat energy will always travel from a temperature material to a lower temperature material. Heat Transfer Conduction is when heat energy travels along a. are the best conductors of heat. Convection is when a gas or is heated and rises, drawing colder air in underneath it. This causes the air to and transfer heat energy. Radiation Objects give out energy as radiation. Very hot objects glow red or even white hot. IR radiation does not need a to travel through. higher, Celsius, material, energy, Metals, solid, infrared, Joules, heat, lower, liquid, circulate 1 P a g e

2 Lesson 2: Cutting down heat loss Heat can be lost from a house in 5 ways: o roof - reduced using cavity glass o walls reduced using cavity fibre o reduced using double and UPVC frames o doors reduced using excluders and UPVC doors o reduced using and underlay floor, glazing, fibre, glass, carpet, windows, draught 2 P a g e

3 Lesson 4: Cavity wall insulation Originally houses were built with a wall. However, this was not a very good method of retaining so instead a second wall was introduced creating a. This cavity is now filled with some insulating that contains pockets which reduces heat loss by conduction and. The new method saves both heat energy and. cavity, money, single, foam, air, heat, convection, 3 P a g e

4 Lesson 5: Energy and Power The a device uses in measured in Joules (J). The amount of energy a device uses every second is called its, measured in watts (W) or (kw) 1kW = W How to calculate the energy used by appliances Measuring energy used in the home in joules (J) gives very numbers. Instead the energy used by electric appliances is measured in a unit of kilo-watt-hours ( ) You can work out the energy used in KWh you must know 2 things: o the appliance s in Watts or kilowatts from its plate, o the number of the appliance is used Now these to find energy in kwh Example problem o - = kilowatts x hours Q. An electric fire has a power rating of 2000W. If it is on for 4 hours how many kwh of energy does it use? A. kilowatts, energy, 1000, large, power, Kilowatt-hours, multiply, wattage, kwh, power, hours 4 P a g e

5 Lesson 6 Paying for electricity The electricity companies their users for each kwh of energy they use. This is called the = kwh x tariff E.g the tariff may be / (each kwh costs 10p) Example problem Q. How much would it cost to run a 2kW heater for 3h? Cost, charge, TARIFF, 10p/kWh 5 P a g e

6 Lesson 8 Future energy The pie chart shows the various of energy we use: nuclear, wind, solar, hydro, gas, coal, micro-generation, wave and biomass. Just energy source will not supply all our needs. There will need to be a mix of more than one source. The sources we use must be. That means they will provide clean,, plentiful and affordable energy. We must avoid using energy sources that lead to an in the levels of carbon dioxide in the as this leads to global warming. E.g. we must avoid burning fuels (coal,, gas) as this would release more into the atmosphere. reliable, future, increase, oil, CO 2,fossil, sources, sustainable, one, atmosphere 6 P a g e