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Electrical Efficiency

Electrical Efficiency LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices. Electrical Efficiency Electrical Power: the rate at which electrical energy is produced or used. -measured in Watts (W)

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Electrical Efficiency

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  1. Electrical Efficiency LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  2. Electrical Efficiency Electrical Power: the rate at which electrical energy is produced or used. -measured in Watts (W) -one Watt is equal to one Joule of energy used per second LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  3. Electrical Efficiency Electrical Power: the rate at which electrical energy is produced or used. -measured in Watts (W) -one Watt is equal to one joule of energy used per second e.g. 100 W light bulb uses four times as much energy per second as a 25 W bulb. LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  4. Electrical Efficiency kilowatt-hour (kWh): the SI unit for measuring electrical energy usage -1 kWh is the use of one killowatt of energy for one hour -3600 times as much energy as 1 Joule LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  5. Electrical Efficiency LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  6. Electrical Efficiency Efficiency: comparison of the energy output of a device with the energy supplied e.g. Clothes dryers -older clothes dryer uses 800 kWh per year -new clothes dryer uses 300 kWh per year -they both do the same job so the new dryer is more than twice as efficient LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  7. Electrical Efficiency Calculating efficiency of a Device: percent efficiency = energy in x 100% energy out LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  8. Electrical Efficiency Calculating efficiency of a Device: percent efficiency = energy in x 100% energy out short form: LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  9. Electrical Efficiency Example: A light bulb uses 100 J of energy and produces 35 J of light energy. Calculate the energy efficiency of the light bulb. LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  10. Electrical Efficiency Example: A light bulb uses 100 J of energy and produces 35 J of light energy. Calculate the energy efficiency of the light bulb. Given: Eout = 35 J Ein = 100 J Unknown: % efficiency LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  11. Electrical Efficiency Example: A light bulb uses 100 J of energy and produces 35 J of light energy. Calculate the energy efficiency of the light bulb. Given: Eout = 35 J Ein = 100 J Unknown: % efficiency Ein Select: % efficiency = _____ x 100% Eout LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  12. Electrical Efficiency Example: A light bulb uses 100 J of energy and produces 35 J of light energy. Calculate the energy efficiency of the light bulb. Ein Select: % efficiency = _____ x 100% Eout Solve: % efficiency = 100 J x 100% 35 J =35% LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  13. Electrical Efficiency Try this: A toaster oven uses 1200 J of energy to produce 850 J of thermal energy. Calculate the efficiency of the toaster oven. LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  14. Electrical Efficiency Try this: A toaster oven uses 1200 J of energy to produce 850 J of thermal energy. Calculate the efficiency of the toaster oven. Given: Eout = 850 J Ein = 1200 J Unknown: % efficiency Select: Ein % efficiency = _____ x 100% Eout LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  15. Electrical Efficiency Try this: A toaster oven uses 1200 J of energy to produce 850 J of thermal energy. Calculate the efficiency of the toaster oven. Solve: % efficiency = 850 J x 100% 1200 J = 71% therefor the toaster oven is 71% efficient LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  16. Electrical Efficiency Cost of Operating Electrical Devices: LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  17. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  18. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. Given: power = 75 W = 0.075 kW LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  19. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. Given: power = 75 W = 0.075 kW time = 24 hours per day for 365 days = 8760 hours cost = 5.6¢/kWh LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  20. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. Unknown: cost to operate Select: cost to operate = power x time x cost of used electricity LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  21. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. Unknown: cost to operate Select: cost to operate = power x time x cost of used electricity Solve: cost to operate = 0.075 x 8760 x 5.6 = 3679¢ ($36.79) LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  22. Electrical Efficiency Example: a laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6¢/kWh. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day. Unknown: cost to operate Select: cost to operate = power x time x cost of used electricity Solve: cost to operate = 0.075 x 8760 x 5.6 = 3679¢ ($36.79) LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  23. Electrical Efficiency Try this: Calculate the cost of operating a 1500W hair dryer to dry your hair for 6 minutes per day for 3 days. The cost of electricity is 5.6¢/kWh LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  24. Electrical Efficiency Try this: Calculate the cost of operating a 1500W hair dryer to dry your hair for 6 minutes per day for 3 days. The cost of electricity is 5.6¢/kWh Given: power = 1500 W = 1.500 kW time = 6 minutes per day for 3 days = 6 min x 3 = 18 min = 0.30 hours cost = 5.6¢/kWh Unknown: cost to operate LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

  25. Electrical Efficiency Try this: Calculate the cost of operating a 1500W hair dryer to dry your hair for 6 minutes per day for 3 days. The cost of electricity is 5.6¢/kWh Select: cost to operate = power x time x cost of used electricity Solve: cost to operate = 1.500 x 0.30 x 5.6 = 2.52¢ LG: to understand how energy efficiency is calculated & use it to determine energy efficiency of household electrical devices

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