1 / 17

Section 12.3 Electrical Energy & Section 12.7 Electrical Power and Efficiency Mr.Shishis

Section 12.3 Electrical Energy & Section 12.7 Electrical Power and Efficiency Mr.Shishis. 12.3 Electrical Energy: 2 Sources. 1. Battery. 2. Electric Generating Station. 12.3 Electrical Energy. Energy provided by the flow of electrons in a circuit . It is measured in joules (J).

jorryn
Download Presentation

Section 12.3 Electrical Energy & Section 12.7 Electrical Power and Efficiency Mr.Shishis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Section 12.3 Electrical Energy & Section 12.7 Electrical Power and EfficiencyMr.Shishis

  2. 12.3 Electrical Energy: 2 Sources 1. Battery 2. Electric Generating Station

  3. 12.3 Electrical Energy • Energy provided by the flow of electrons in a circuit. It is measured in joules (J). • Electric cells produce small quantities of electrical energy and are useful for portable electrical devices

  4. “Battery” Definition • Refers to two or more electric cells in combination. • Converts chemical energy into electrical energy 2 types: 1. Primary cell (Can’t be recharged) 2. Secondary cell (Rechargeable)

  5. Fuel Cell • Produces electric energy by converting hydrogen and oxygen into water! • Water is the waste product. • Is this form good for the environment?

  6. Fuel Cell Vehicle

  7. Section 12.7: Electrical Power & Efficiency • Electrical Power: The rate at which electrical energy is produced or used. • Unit: watt (W) • 1 watt = 1 Joule per second (1 J/s) • The higher the wattage, the more electric energy is used or produced by a device

  8. Measuring Electrical Energy Usage • Electric generating stations: Power rating of megawatts (MW) or gigawatts (GW) • Electricity Meters: keep track of how much electrical energy is used in homes, schools and businesses (use kilowatt hour or KW*h)

  9. Efficient Devices • Efficiency: comparison of the energy output of a device with the energy supplied. • Example: In typical light bulb, 90% electrical energy converted to heat & 10% to light!

  10. Energuide and Energy Star Labels

  11. If you were buying an appliance, what is important to you? • Price • Cost of operating the device over time • All household appliances are sold with the Energuide label (estimate of how much electricity the appliance will use in 1 year) • Energy Star symbol: Products that meet the minimum level of efficiency.

  12. Calculating the Efficiency of a Device % efficiency= energy out x 100% or energy in % efficiency= Eout x 100% Ein Where Eout: measure of how much useful energy the device puts out Ein: measure of how much energy the device requires

  13. Sample Problem 1, pg 533 • A light bulb uses 100 J of energy and produces 35 J of light energy. Calculate the % efficiency of the light bulb. Given: Eout= 35 J Ein= 100J % efficiency= Eout x 100% Ein % efficiency= 35J x 100% 100J % efficiency= 0.35 x 100%, which is 35% Therefore, the efficiency of the light bulb is 35%

  14. You try one... • Practice problem, pg 533: A toaster oven uses 1200J of energy to produce 850J of thermal energy. Calculate the % efficiency of the toaster oven.

  15. Cost of Electricity • In Ontario, current cost of electricity is regulated at 5.6 cents/kW*h. • How much would it cost to use a laptop computer for 1 year? • You need to know the power rating of the laptop in kilowatts and the length of time that it is operating in hours.

  16. Cost to operate... Cost to operate= power used x time x cost of electricity Sample Problem (pg 534 in textbook): A laptop computer uses a 75 W adapter when it is plugged in. Electricity costs 5.6 cents/kW*h. Calculate how much it would cost to operate the laptop for 1 year for 24 hours per day? Let’s do it on the board... Try practice problem on pg 534 in textbook...

  17. Homework/Assignments 1. HW: Section 12.3 (questions #3-6, pg 514) 2. HW: Section 12.7 (questions# 1-7, pg 535) 3. Assn: Section 12.8 (Energy Production Assignment due Friday Dec 3/2010) 4. Assn: Start Energy Audit (Section 12.9) 5. Quiz on Chapter 12 (Friday Dec 3/2010)

More Related