Term
| Give three ways that heat energy can be transferred. |
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Definition
1. Radiation
2. Conduction
3. Convection
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Term
Complete the sentence
'The bigger the temperature difference between the body and its surroundings....' |
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Definition
| '....the faster heat energy is transferred by heating.' |
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Term
Complete the sentence
'An object that's hotter than its surroundings _____ more radiation than it _______.' |
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Definition
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Term
Complete the sentence
'An object that's cooler than its surroundings _______ more radiation than it _____.' |
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Definition
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Term
| What surfaces are better to absorb infared radiation? |
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Definition
| Dark, matt surfaces are much better than light shiny surfaces. |
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Term
| What happens when you heat a substance? |
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Definition
| It gives its particles more kinetic energy allowing them to vibrate and move faster causing solids to melt and liquids to boil. |
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Term
| Describe how an Immersion Heater Works. |
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Definition
1.Heat energy is transferred from the heater at the bottom by conduction (particle collisions)
2. The particles near the heater gain more energy allowing them to move faster
3.This means there is more distance between them and the water becomes less dense
4. Hotter, denser water rises above the cooler denser water
5.The cold water is then heated and the process repeats
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Term
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Definition
| Convection is when more energetic (hotter) particles rise above less energetic (cooler) particles because of the changes in density. |
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Term
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Definition
| When a gas turns into a liquid because the particles slow down and lose kinetic energy meaning the particles are pulled together. |
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Term
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Definition
| When a liquid turns into a gas because the particles gain more kinetic energy to escape. |
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Term
| Give and explain 3 reasons why the Rate of Evaporation would be faster. |
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Definition
1.Temperature is higher - more particles will have enough energy to escape
2.Density is lower - the forces between the particles will be weaker
3.Surface area is larger - more particles will be near enough to the surface to escape the liquid
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Term
Give and explain 3 reasons why the Rate of Condensation would be faster. |
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Definition
1.Temperature of the gas is lower - more particles will slow down and clump together
2. Temperature of the surface the gas touches is lower
3. Density is higher - the forces between the particles will be stronger
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Term
Complete the sentence
'The ______ the surface area the ____ infared waves can be _______ from the surface - so the _______ the transfer of heat.' |
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Definition
| Bigger, More, Emitted, Quicker |
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Term
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Definition
| Used on car and motorbike engines to increase surface area so heat is radiated away quicker and the engine cools quicker. |
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Term
| What happens to the hairs on your skin when you're cold? |
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Definition
| They stand up to trap a thicker layer of insulating air around your body. This limits heat loss by convection. |
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Term
| Why do some people's skin go pink when they're hot? |
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Definition
| When your body is hot it dialates the blood vessels in your skin to keep you cool. |
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Term
| What is Cavity Wall Insulation? |
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Definition
| Foam squirted into the gap between bricks stopping convection currents being set up in the gap and radiation across the gap. The insulating foam and the air pockets trapped in it (air is an insulator) also help reduce heat loss by conduction. |
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Term
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Definition
| A thick layer of fibre glass wool laid out across the loft floor and ceiling reduced heat loss by conduction and convection. |
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Term
| What is draught proofing? |
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Definition
| Strips of foam and plastic around doors and windows stop draughts of cold air blowing in, reducing heat loss by convection. |
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Term
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Definition
| U-Values show how fast heat can transfer through a material. Heat transfers faster with materials which have a higher U-Value. So materials with a lower U-Value are better insulators. |
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Term
| What does the term 'Cost Effective' mean in relation to insulators? |
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Definition
| The most cost effective methods of insulating the home are the cheapest with the shortest payback time. |
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Term
What does the term 'Most Effective' mean in relation to insulators?
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Definition
| The most effective methods of insulating the home are the ones that have the greatest annual saving (they save you the most money on heating bills). |
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Term
| What is Specific Heat Capacity? |
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Definition
| Specific Heat Capacity is how much energy things can store - the amount of enerygy needed to raise the temperature of a 1kg substance by 1oC. |
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Term
| What is the equation for Specific Heat Capacity? |
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Definition
E = m x c x ΔT
E= Energy Transferred / Heat (J)
m = Mass (kg)
c = Specific Heat Capacity (J/kgoC)
ΔT = Temperature Change (oC) |
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Term
| Name two materials in a Heater and explain the reasons for the use of each material. |
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Definition
Water - Large Specific Heat Capacity and a Liquid so can be pumped around in pipes.
Concrete (Electric storage heaters) - Large Specific Heat Capacity |
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Term
| Name the nine types of energy. |
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Definition
1. Electrical
2. Light
3. Sound
4. Kinetic
5. Nuclear
6. Thermal
7. Gravitational Potential
8. Elastic
9. Chemical |
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Term
| Give an example of Gravitational Potential Energy. |
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Definition
| Possessed by anything that can fall. |
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Term
Give an example of Nuclear Energy. |
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Definition
| Released only from nuclear reactions. |
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Term
Give an example of Elastic Potential Energy. |
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Definition
| Stretched springs, elastic, rubber bands etc. |
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Term
| Name the three types of stored energy (when the energy is not dong anything). |
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Definition
1. Gravitational Potential Energy
2. Elastic Potential Energy
3. Chemical Energy |
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Term
| What is the Conservation of Energy Principle? |
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Definition
| Energy can be transferred usually from one form to another, stored or dissipated (the energy is spread out and lost) - But it can never be created or destroyed. |
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Term
| What are the two stages in the transfer of energy in a battery. |
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Definition
| Chemical Energy → Electrical Energy and Heat Energy |
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Term
| How do you calculate the Efficiency of Machines? |
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Definition
Useful energy out
_________________
Useful energy in
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Term
| What do Heat Exchangers do? |
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Definition
| Reduce the amount of energy wasted by a machine by pumping a cool fluid through the escaping heat and using it for other purposes. |
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Term
| What is a Sankey diagram? |
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Definition
| A diagram that makes it easy to see at a glance how much of the total energy is wasted compared to useful energy. (The thicker the arrow the more energy it represents) |
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Term
| What is a Kilowatt-hour (kWh)? |
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Definition
| The amount of electrical energy used by a 1kW appliance left of for 1 hour. |
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