Physics 1 Revision Lesson 3 Energy transfer and

Physics 1 Revision Lesson 3 Energy transfer and efficiency

Energy transfer and efficiency

Energy cant be created or destroyed, it just turns into another form Energy transfer diagrams show input, useful and wasted energy Wasted energy is usually heat & sound. This energy goes into the surroundings Chemical kinetic (useful) sound (wasted) heat (wasted)

An appliance that wastes les energy is called energy efficient Efficiency = useful energy / total energy Energy efficient appliances can save you money Energy is measured in Joules (J)

Filament light bulb 100 J 10 J electrical light energy (input) (output) 90 J heat energy (wasted) Energy efficient light bulb 20 J 10 J electrical light energy (input) (output) 10 J heat energy (wasted) Sankey diagrams are a way to show energy efficiency The thicker the arrow , the more energy input/ output

How long it takes to recover the costs of an appliance is called pay back time If loft insulation costs £ 200 to install and saves you £ 50 a year in heating bills… the pay back time is 4 years Ways to make a home energy efficient Energy saving light bulbs Cavity wall insulation Loft insulation Draft excluders Double glazing The double-glazing for a house costs £ 3, 000 but saves £ 150 per year in fuel costs. What is its payback time? The cavity wall insulation in a house costs £ 6000 to install. It has a payback time of 15 years. How much money does the insulation save each year in fuel costs?

Transferring electrical energy

Electrical energy is measured in k. W/h Electrical energy = power (k. W) x time (h) The longer you use an appliance for the more electrical energy it will transfer

Electricity costs money The electricity company charges you for every you use unit 1 unit = 1 k. W/h cost = number of units x cost per unit Example: How much would 10 units of electricity cost at a price of 9 p per unit?

Key words and statements

Energy transfer and efficiency Input energy How well a device transforms input energy into useful energy Useful energy The unit for energy Wasted energy The amount of energy in joules that is transferred into the wrong type of energy Energy efficiency The amount of electrical energy used and can be measured by power (k. W) x time (h) Joules The unit is k. W/h. The amount of energy in joules that is transferred into the right type of energy Pay back time Is equal to 1 k. W/h Electrical companies charge consumers by units Electrical energy transfer Number of joules that enters the device Unit of electricity The time it takes to recover the cost of an energy efficient appliance before you can start saving money

Energy transfer and efficiency Input energy How well a device transforms input energy into useful energy Useful energy The unit for energy Wasted energy The amount of energy in joules that is transferred into the wrong type of energy Energy efficiency Is measured in k. W/h The amount of electrical energy used and can be measured by power (k. W) x time (h) Joules The amount of energy in joules that is transferred into the right type of energy Pay back time Is equal to 1 k. W/h Electrical companies charge consumers by units Electrical energy transfer Number of joules that enters the device Unit of electricity The time it takes to recover the cost of an energy efficient appliance before you can start saving money

Energy transfer and efficiency Energy cannot be… Turns more of it’s input energy into useful energy and wastes less energy Wasted energy is usually… But will save money in the long term. The time is takes to recover the cost of the device is called pay back time An energy efficient device… Heat or sound and goes into the surroundings A Sankey diagram… The more electrical energy it will transfer Energy efficient devices usually coast money to install… You use the appliance for longer and when the appliance uses a greater amount of power The longer an appliance is used for… Created or destroyed The cost of using an appliance will increase when… It will take 8 years to pay back the cost If solar panels cosy £ 2000 pounds to install and it saves £ 250 pounds in electricity bills per year… Is a graph showing input, useful and wasted joules

Energy transfer and efficiency Energy cannot be… Turns more of it’s input energy into useful energy and wastes less energy Wasted energy is usually… But will save money in the long term. The time is takes to recover the cost of the device is called pay back time An energy efficient device… Heat or sound and goes into the surroundings A Sankey diagram… The more electrical energy it will transfer Energy efficient devices usually cost money to install… You use the appliance for longer and when the appliance uses a greater amount of power The longer an appliance is used for… Created or destroyed The cost of using an appliance will increase when… It will take 8 years to pay back the cost If solar panels cosy £ 2000 pounds to install and it saves £ 250 pounds in electricity bills per year… Is a graph showing input, useful and wasted joules