 What is “green energy”?  What is a “carbon footprint”?  Why should you care?  How can you reduce your carbon footprint? p142

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<ul><li> Slide 1 </li> <li> Slide 2 </li> <li> Slide 3 </li> <li> What is green energy? What is a carbon footprint? Why should you care? How can you reduce your carbon footprint? p142 </li> <li> Slide 4 </li> <li> What do you see in the cartoon? Turn and tell your partner 2 things Share out Record in your notebook p142 </li> <li> Slide 5 </li> <li> Record in your notebook Usually, when you need electricity, all you have to do is plug an appliance into the wall How is the electricity that you use generated? Make a list of energy sources Compare with a partner p142 </li> <li> Slide 6 </li> <li> 1.) Where does electricity come from? How does it get to your house? All Sacramento county households get their electricity from SMUD (Sacramento Metropolitan Utility District) and natural gas from PG&amp;E (Pacific Gas and Electricity) https://www.smud.org/en/about-smud/company- information/power-sources.htm https://www.smud.org/en/about-smud/company- information/power-sources.htm Ask for a copy of your most recent SMUD bill. Make a copy and bring it to class. p143 </li> <li> Slide 7 </li> <li> Basic (world)Basic (USA)Dream house Compare with a partner p143 </li> <li> Slide 8 </li> <li> Highest energy user: Air conditioning/heaterHot water heater Clothes dryerRefrigerator freezer Medium energy users: Tv/computersMicrowave DishwasherHair dryer Toaster/oven Low energy users: FansLights Stereo/boom boxcoffee maker </li> <li> Slide 9 </li> <li> Using only the items in the bag, make the light bulb glow. Draw a picture in your notebook Explain what you think is happening p144 </li> <li> Slide 10 </li> <li> 1. Electricity is created when electrons move from one place to another. Electricity can also be created when work is done to move a magnet within a coil of wire (generator) 2. Electrons move to places with less negative charge (opposite charges attract, similar charges repel) 3. Energy can be transferred from one type to another. 4. Power companies (like SMUD) get electricity from different sources (hydro, gas, solar, wind, geothermal) 5. For an electric current to exist in a circuit, the circuit must form a closed loop. Switches are used to open/close a circuit. Metals conduct easily. Other materials do not and act as insulators. 6. A fuse burns out if the current becomes too large 7. As the energy output of a circuit increases, the energy needed also increases p145 </li> <li> Slide 11 </li> <li> Equipment in the box on the lab bench Hand generators can break (and cost $$) Crank them slowly and gently Get your notebook stamped when you are finished and put everything back in the box. Answer CU (p601) 1-3 PtoGo (p604) 1-9 Get your notebook stamped again P144 </li> <li> Slide 12 </li> <li> What do you see in the picture? Turn and share 2 things that you see with your neighbor What do you think? What is electricity and how does it move through a circuit? Record your ideas in your notebook Share out P146 </li> <li> Slide 13 </li> <li> Volunteer to be the battery: Volunteer to be the light bulb (how do we know when the bulb is on?) Everyone else is an electric charge (electron)in the circuit Arrange yourselves into a complete circuit Round 1 </li> <li> Slide 14 </li> <li> ROUND 1 (RECORD IN YOUR NOTEBOOK)ROUND 2: ADD VOCALS The battery (source of beads) gave each unit of charge (student electron) a certain amount of energy (one bead).The charge then gave that energy to the light bulb (dancing student) who converted the energy into light, The charges (student electrons) continue back to the battery to get more energy and repeat the process. 1 volt battery means 1 amp means The battery announces the battery voltage is 1 volt which equals one joule of energy for each coulomb of charge Any student receiving a block responds one coulomb of charge receiving one joule of energy Teacher says please move along, one coulomb per second is one ampere (amp) of current The light bulb says I just received one joule of energy from that coulomb of charge p146 </li> <li> Slide 15 </li> <li> Round 3 Voltage=3 volts means (battery gives each charge 3 joules of energy) Current=1 amp means ( coulomb of charge moves by every second) Record what happens Round 4 Voltage=1volt means Current=2 amps means Record what happens p146 </li> <li> Slide 16 </li> <li> a.) there is a 5 volt battery b.) current is 3 amps c.) there is a two volt battery d.) the current is increased to 5 amps e.) the two-volt battery is replaced with a four-volt battery f.) the current increases from 2 amps to 3 amps p147 </li> <li> Slide 17 </li> <li> Now we need 2 light bulbs. 1a.) Describe what will happen if we put 2 bulbs in our circuit, one right after the other. In order to have any light in the second bulb, an electron (student) must keep some of the energy from the first bulb (so less energy goes to the first bulb) to give to the second. This is called resistance. How much energy goes to the first bulb depends on the bulb. For now, half of the energy will go to the first bulb, and half to the second bulb. p147 </li> <li> Slide 18 </li> <li> 2a.) Since the brightness of a bulb depends on how much energy is used up in the bulb during a given time, how would the brightness of each of the 2 bulbs in the series circuit compare with the brightness of a single bulb hooked up to the same battery? 3 A) 4 light bulbs in series result in B) two light bulbs and a 3-volt battery C) two light bulbs, but twice as much current D) two different kinds of light bulbs in series Get a stamp P147-8 </li> <li> Slide 19 </li> <li> Get a stamp CU (p610) 1-4 Get a stamp PtoGo (p612-613) 1-4 Get a stamp 1 Bulb2 BulbsWhich is brighter? voltagecurrentvoltagecurrent 1111One bulb 1121 1112 1122 2241 2223 4132 </li> <li> Slide 20 </li> <li> 8. Electrical power is the speed that energy is transferred. Power is measured in Watts (W) 9. Electric potential or voltage is the potential energy per unit of charge, and is measured in volts 1 volt=1 joule/charge 10. Current is the amount of charge per unit of time that flows past a point and is measured in amperes (amps) 1amp=1 charge/second 11. Resistors are electronic devices (like light bulbs) that resist the flow of electric charge 12. In a series circuit there is one path for current to follow. The sum of the voltage dropped at each resistor is equal to the total voltage supplied to the circuit (2 light bulbs in series: each gets the voltage and are therefore the brightness) p145 </li> <li> Slide 21 </li> <li> What do you see in the picture? Turn and share 2 things that you see with your neighbor What do you think? When one light bulb in your house goes out, can the other light bulbs remain on? Can a circuit be set up to allow this? Record your ideas in your notebook Share out p149 </li> <li> Slide 22 </li> <li> Back to our electron shuffle model Round 1: Set up a series circuit. What happens again when we put a second bulb into this series circuit? Draw a picture of this circuit. Round 2: Now we are going to make a parallel circuit. At a certain point, a junction, electrons will have to choose which light bulb to give their energy to. Draw a picture of this circuit. p149 </li> <li> Slide 23 </li> <li> The battery announces the battery voltage is 1 volt which equals one joule of energy for each coulomb of charge Any student receiving a bead responds one coulomb of charge receiving one joule of energy Teacher says please move along, one coulomb per second is one ampere (amp) of current The light bulb says I just received one joule of energy from that coulomb of charge Record in your notebook: 1 volt battery means (battery gives each charge 1 joules of energy) 1 amp means (1 coulombs of charge move by every second) 3.)Record what happens: The battery: The electrons: The light bulbs: p149 </li> <li> Slide 24 </li> <li> Each light bulb receives one joule (bead) for each coulomb of charge (from each student electron) that passes through the light bulb. p149 </li> <li> Slide 25 </li> <li> (1)(1)/2= Because the current divides equally among the light bulbs, each light bulb receives an equal share of the coulomb of charge. 2 bulbs means each bulb gets one half. </li> <li> Slide 26 </li> <li> The battery announces the battery voltage is 1 volt which equals one joule of energy for each coulomb of charge Any student receiving a block responds one coulomb of charge receiving one joule of energy Teacher says please move along, one coulomb per second is one ampere (amp) of current The light bulb says I just received one joule of energy from that coulomb of charge Record in your notebook: Draw a picture of this circuit p150 </li> <li> Slide 27 </li> <li> Each light bulb receives one joule (bead) for each coulomb of charge (from each student electron) that passes through the light bulb. (same amount as the last round) </li> <li> Slide 28 </li> <li> Three bulbs means each bulb gets 1/3 per second (different amount of current than the last round) </li> <li> Slide 29 </li> <li> Round 4 Voltage=3 volts (battery gives each charge 3 joules of energy) Current=1 amp (1 coulombs of charge move by every second) Round 5 Voltage=1 volt (means) Current=2 amps (means) p150 </li> <li> Slide 30 </li> <li> 7a.) 4 bulbs in a parallel circuit (the current passing by each light bulb would be) (1)(1)/4= One fourth (1/4) coulomb per second or one student passing by every 4 seconds p150 </li> <li> Slide 31 </li> <li> 7b.) three light bulbs and a 3 volt battery (3)(1)/3= Three times the charge means three times as bright Each light bulb receives 1/3 of a coulomb of charge per second=1 ampere p150 </li> <li> Slide 32 </li> <li> 7c.) 3 light bulbs and larger current (2 amps) (1)(2)/3= Each light bulb would still get the same amount of energy per charge (student) passing by, and 1/3 the larger current, but there is twice as much current, so each bulb would get 2/3 amps each p150 </li> <li> Slide 33 </li> <li> 7d.) 4 light bulbs and 6 volts (6)(1)/4 = Each light bulb would receive six joules of energy for every coulomb (student) that passes and each light bulb would receive the current of 1 amp (one student would pass by every 4 seconds) p150 </li> <li> Slide 34 </li> <li> 7e.) 3 bulbs that are not identical Each would get the same amount of energy per charge (student), but different amounts of charge because they are not identical (the number of students passing by per second would vary) p150 </li> <li> Slide 35 </li> <li> Use Phet: Circuit Construction Kit (DC only)Phet: Circuit Construction Kit (DC only) Follow directions and answer questions on the handout (Some properties of electric circuits) Get a stamp when finished CU (p618) 1-4 PtoGo (p621-622) 1-9 Get stamps when finished P150 P151 </li> <li> Slide 36 </li> <li> PART VI ResistanceCurrent0.60Voltage 100.909.00 150.609.00 200.459.00 250.369.00 30 35 40 45 50 55 a) What is the relationship between resistance and current? b) What is the relationship between resistance and voltage? c) Explain PHET: Some Properties of Electric Circuits </li> <li> Slide 37 </li> <li> 13. In a series circuit current flows along one path. In a parallel circuit the current flows along parallel paths. 14. The voltage drop across each branch is equal the total voltage 15. The sum of the current in each branch equals the total current p145 </li> <li> Slide 38 </li> <li> What do you see in the picture? Turn and share 2 things that you see with your neighbor What do you think? What determines the brightness of a bulb? What determines how much current flows in a circuit? Record your ideas in your notebook Share out p151 </li> <li> Slide 39 </li> <li> Today you will use the phet simulation: Circuit Construction Kit (in place of the lab in the text book) All parts should be completed today (before our next class meeting) CU (p626) PtoGo (p629-630) 1-4 CDP 33-2 34-1 p152 </li> <li> Slide 40 </li> <li> 16. Voltmeters are used to measure voltage (which is measured in volts or V) 17. Ammeters are used to measure current (which is measured in amps or I) 18. Resistance is directly proportional to the voltage dropped and inversely proportional to the current 19. Resistance is measured in ohms or 20. Ohms Law: voltage=(current)(resistance) V=IR and I=V/R and R=V/I p145 </li> <li> Slide 41 </li> <li> 6. Your hair dryer has a resistance of 9.6 ohms and you plug it into the bathroom outlet. Assume household voltage to be 120 volts, and that different parts of your house are connected in parallel. a.) What current will it draw? I=V/R=120V/9.6=12.5 amps b.)Suppose that your brother has an identical hair dryer and plugs it into a parallel part of the circuit. What current will the two hair dryers draw? Parallel circuits have the same voltage drop and the same current12.5 amps + 12.5 amps=25 amps total c.) If the maximum current the circuit breaker in the system can handle is 20 amps, what do you think will happen? The circuit breaker will break when the current exceeds 20 amps p153 </li> <li> Slide 42 </li> <li> 8.) A 12 volt battery is hooked up to a 3 ohm resistor. The current through the resistor is I=V/R=12/3=4 amps p153 </li> <li> Slide 43 </li> <li> 9.) A 2 ohm resistor has 4 amps of current running through it. The voltage drop (or potential drop) across the resistor is V=IR=(4)(2)=8 volts p153 </li> <li> Slide 44 </li> <li> What do you SEE in the cartoon? Use what you see, and your prior experience to answer the questions What Do You Think in your notebook What do you think is the function of a fuse or circuit breaker? Exactly what conditions do you think make a fuse blow or a circuit breaker trip? p154 </li> <li> Slide 45 </li> <li> 1.) Watch the following demonstrations on youtube Balloon fuse http://www.youtube.com/watch?v=m3U4k_xTS pU http://www.youtube.com/watch?v=m3U4k_xTS pU Electricity review http://www.youtube.com/watch?v=l0nCSzqefn w&amp;feature=related http://www.youtube.com/watch?v=l0nCSzqefn w&amp;feature=related 1a.) what happens to the light in the video when the fuse blows? p154 </li> <li> Slide 46 </li> <li> 2a.) Why do you think that the fuse blew? b.) Why did the circuit require multiple appliances to blow out the fuse? c.) Explain why the fuse behaves the way it does. p154 </li> <li> Slide 47 </li> <li> ApplianceVoltagePower (Watts)Current (Amps) Hot plate120800 Lamp with 100 Watt bulb 120100 heater120300 4.) Copy the table into your notebook. 5.) Calculate the current for each appliance I=P/V 6.) Find the total current and total power used above. The current rating on the power strip was 10 A. Did the total current of the appliances exceed that rating? CU (p638) 1-4 PtoGo (p641-642) 1-13 CDP 34-2 35-1 p155 </li> <li> Slide 48 </li> <li> 20. Power is the rate at which energy is delivered to an object or a load in a circuit. Power is measured in watts. One Watt is one joule of energy supplied in one second of time (1 W= 1 J/s). For a circuit, the power can be calculated by multiplying current and voltage (P=IV)...</li></ul>