893621
| Question | Answer |
| How does double glazing reduce energy loss? | Double glazing reduces energy loss by conduction. |
| The gap between the two pieces of glass is filled with a gas or contains a vacuum. How does this reduce energy loss by conduction? | - Particles in gas are very far apart; it is very difficult to transfer energy. - There are no particles in a vacuum it is impossible to transfer energy by conduction. |
| How does loft insulation reduce energy loss? | Loft insulation reduces energy loss by conduction and convection. |
| How does loft insulation reduce energy loss by conduction and convection? | Loft insulation reduces energy loss by conduction and convection: - warm air in the home rises - energy is transferred through the ceiling by conduction - air in loft is warmed by the top of the ceiling and is trapped in the loft insulation - both sides of the ceiling are at the same temperature so no energy is transferred |
| What can happen without loft insulation? | Without loft insulation, the warm air in the loft can more by convection and heat the roof tiles; energy is transferred to the outside by conduction. |
| How will hot air rise into the loft only? | Hot air will only rise into the loft if the loft-hatch is open. |
| How does cavity wall insulation reduce energy loss? | Cavity wall insulation reduces energy loss by conduction and convection. |
| How does cavity wall insulation reduce energy loss by conduction and convection? | The air in the foam is a good insulator and the air cannot move by convection because it is trapped in the foam. |
| Why do insulation blocks that are used to build new homes have shiny foil on both sides? | Insulation blocks used to build new homes have shiny foil on both sides to reduce energy transfer by radiation. |
| How do the insulation blocks that are used to build new homes which have shiny foil on both sides reduce energy transfer by radiation? | Energy from the Sun in reflected back to keep the home cool in summer and energy from the home is reflected back to keep the home warm in winter. |
| Name the three ways in which energy can be transferred. | - Conduction - Convection - Radiation |
| How is energy transferred by conduction? | Energy can be transferred by conduction due to the transfer of kinetic energy between particles. |
| How is energy transferred by convection? | Energy is transferred by convection as a gas expands when it is heated. This makes it less dense so it rises. |
| What is the unit of density? | The unit of density is kg/m³ or g/m³. |
| What is the equation for density? | density = mass/volume |
| How is energy transferred by radiation? | Radiation does not need a material to transfer energy. Energy can be transferred through a vacuum. |
| How can you calculate energy efficiency? | energy efficiency = useful energy output (x 100%) / total energy input |
| How can energy transformations be shown? | Energy transformations can be shown by Sankey diagrams. |
| Draw an example of a Sankey diagram for a light bulb when the total energy input is 100J, 75J is useful energy output and 25J is energy lost to the environment. | |
| Fill in the gaps: Energy from the ...... (....) is lost to the .... (...........). | Energy from the source (home) is lost to the sink (environment). |
| Different amounts of insulation cost different amounts and save different amounts of energy. Write the equation for payback time. | payback time = cost of insulation / annual saving |
| Fill in the gaps: Everything that transfers ...... will ..... some of that energy as .... to the ............. | Everything that transfers energy will waste some of that energy as heat to the surroundings. |
| Buildings that are well insulated and where little energy is lost to the surroundings are what? | Buildings that are energy efficient are well insulated and little energy is lost to the surroundings. |
| Designers and architects have to make sure that......... | Designers and architects have to make sure that as little energy as possible is wasted. |
Want to create your own Flashcards for free with GoConqr? Learn more.