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Ch 6 Electricity for everyone

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### Ch 6 Electricity For Everyone efficient.

Whiteboard

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

What do you see in the cartoon?

Turn and tell your partner 2 things

Share out

Record in your notebook

Investigation #1 (p598)p142

What do you Think? (p598)

p142

- 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

Part A

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&E (Pacific Gas and Electricity)
- 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.

Appliances by energy use

Highest energy user:

Air conditioning/heater Hot water heater

Clothes dryer Refrigerator

freezer

Medium energy users:

Tv/computers Microwave

Dishwasher Hair dryer

Toaster/oven

Low energy users:

Fans Lights

Stereo/boom box coffee maker

How many physics students does it take to light a light bulb?

p144

- Using only the items in the bag, make the light bulb glow.
- Draw a picture in your notebook
- Explain what you think is happening

Electricity model: Section 1 bulb?DQ: How does electricity work?

p145

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

Part B (p599-600 bulb?) Steps 1-3 only

P144

- 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

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

Section 2 (p606-609)P146

Volunteer to be the battery: you see with your neighbor

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

Investigation 2: The Electron ShufflePart A: Modeling a Simple Circuitp146 you see with your neighbor

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”

This is the ELECTRON SHUFFLE. What are the variables that we could change?

p146

- 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

a.) there is a 5 volt battery could change?

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

On your own p608 #9Record how the electron shuffle would change under the following conditions:p147

- Now we need 2 light bulbs. could change?
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

Part B: Modeling a series circuit- 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

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 ½ the voltage and are therefore ½ the brightness)

p145

Electricity model: Section 2What 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

Investigation 3 Series and Parallel Circuits (p614-617)Back to our electron shuffle model… you see with your neighbor

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

InvestigationPart A; Modeling a parallel circuitRound 2 (2 bulbs in parallel): you see with your neighborjan-jun go to bulb one jul-dec bulb two

p149

- 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:

Each light bulb receives one joule (bead) for each coulomb of charge (from each student electron) that passes through the light bulb.

p149

4a.) The battery provided each coulomb of charge with one joule of energy. How much energy did each light bulb get from each coulomb of charge?

(1)(1)/2= of charge (from each student electron) that passes through the light bulb.

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.

4b.) The charges left the battery at the rate of one coulomb per second. What was the current through each light bulb?Round 3 (3 bulbs in parallel): of charge (from each student electron) that passes through the light bulb. jan-apr bulb one, may-aug bulb two, sep-dec bulb three

p150

- 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

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)

4c.) The battery provided each coulomb of charge with one joule of energy. How much energy did each light bulb get from each coulomb of charge?

Three bulbs means each bulb gets of charge (from each student electron) that passes through the light bulb. 1/3 per second (different amount of current than the last round)

4d.) The charges left the battery at the rate of one coulomb per second. What was the current through each light bulb? (1)(1)/3=Continue recording in your notebook: of charge (from each student electron) that passes through the light bulb.

p150

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…)

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

How does a parallel circuit change under these conditions? (1 volt and 1 amp)7b.) three light bulbs and a 3 volt battery each light bulb would be…)

(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

How does a parallel circuit change under these conditions? (3 volt and 1 amp)7c.) 3 light bulbs and larger current (2 amps) each light bulb would be…)

(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

How does a parallel circuit change under these conditions? (1 volt and 2 amp)7d.) 4 light bulbs and 6 volts each light bulb would be…)

(6)(1)/4 =

Each light bulb would receive six joules of energy for every coulomb (student) that passes and each light bulb would receive ¼ the current of 1 amp (one student would pass by every 4 seconds)

How does a parallel circuit change under these conditions? (6 volt and 1 amp)p150

7e.) 3 bulbs that are not identical each light bulb would be…)

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)

How does a parallel circuit change under these conditions? (1 volt and 1 amp)p150

Use each light bulb would be…)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

Part B: Comparing series and parallel circuitsP150

P151

PHET: Some Properties of Electric Circuits each light bulb would be…)

Part VI

a) What is the relationship between resistance and current?

b) What is the relationship between resistance and voltage?

c) Explain

This is OHM’S Law: V=IR13. 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

Electricity model: Section 3What 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

Section 4 (p623)p151

Today you will use the you see with your neighborphet 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

investigation16. 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 Ω

20. Ohm’s Law: voltage=(current)(resistance) V=IR and I=V/R and R=V/I

Electricity model: Section 4p145

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 current…12.5 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

PtoGo (p629)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

PtoGo (p629)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

PtoGo (p630)p153

What do you SEE in the cartoon? it. The voltage drop (or potential drop) across the resistor is

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

Section 5 electric power: load limit (p631-643)1.) Watch the following demonstrations on it. The voltage drop (or potential drop) across the resistor isyoutube

Balloon fuse http://www.youtube.com/watch?v=m3U4k_xTSpU

Electricity review http://www.youtube.com/watch?v=l0nCSzqefnw&feature=related

1a.) what happens to the light in the video when the fuse blows?

p154

Investigation2a.) Why do you think that the fuse blew? it. The voltage drop (or potential drop) across the resistor is

b.) Why did the circuit require multiple appliances to blow out the fuse?

c.) Explain why the fuse behaves the way it does.

Teacher demo: when you plug a hot plate, a lamp with a 100 watt bulb, and a heater into a power strip and turn them all on at the same time, the power strip will turn itself off.

p154

Below are the appliance ratings: it. The voltage drop (or potential drop) across the resistor is

p155

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

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)

21. When the flow of electric charge, or current, occurs easily in a material it is called a good electric conductor. When the material does not allow charge to flow easily (or not at all) it is called an insulator.

22. Fuses and circuit breakers are used as safeguards to protect the circuit from too much current and prevent electrical fires from starting. A fuse consists of a wire that will melt when too much current flows through it, thus opening the circuit. A fuse must be replaced when blown (to make a closed circuit). A circuit breaker is a switch that opens when too much current flows through it. A circuit breaker must be reset when tripped for current to resume flowing.

23. The power (and current) drawn by a circuit depends upon the voltage of the circuit and the resistance of the circuit. Decreasing the resistance of a circuit increases the power (and current) for a fixed voltage.

p157

Electricity model: Section 5What do you see? Many electrical switches are operated manually (by hand), and many others are automatic, turning appliances on and off in response to a variety of conditions.

List at least 3 different kinds of automatic switching devices in the picture.

What are the conditions that cause the on/off action of the switch?

Section 6 CVR in Parallel and Series: Who’s in control? (p644-659)p158

Today you will use the manually (by hand), and many others are automatic, turning appliances on and off in response to a variety of conditions.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 (p654) 1-3

PtoGo (p658-659) 1-13

CDP 35-2 35-3

p158

Investigate24. Switches are used to control the total circuit or part of a circuit.

25. Energy and charge are conserved in a circuit. Using these principles and Ohm’s Law results in the following relationships for series and parallel circuits:

Series: Parallel:

Vtotal = V1 + V2 + V3 etc. Vtotal = V1 = V2 = V3 etc.

Itotal = I1 =I2 =I3 etc. Itotal = I1 + I2 + I3 etc.

R total = R1 + R2 + R3 etc. 1/Rtotal= 1/R1 + 1/R2 + 1/R3 etc.

26. For any junction in a circuit, the current flowing into the junction must equal the current leaving the junction.

27. The energy consumed in the parts of a circuit is equal to the the energy supplied by the power source

28. Adding resistance in parallel decreases the circuit resistance and increases the circuit current and power.

p157

Electricity model: Section 6What is an electromagnet? How does it work? of a circuit.

Draw and label the parts of an electromagnet

What is a simple test to tell if an electromagnet is working?

Video 1: http://www.youtube.com/watch?v=emlzh9XXWgQ

Video2: http://www.youtube.com/watch?v=frYorKTKdeI

Video 3: http://www.youtube.com/watch?v=_ygmHnjNYNo

How can electricity create a magnet?p154

Use the PHET simulation of a circuit.Magnets and electromagnets

http://phet.colorado.edu/en/simulation/magnets-and-electromagnets

Get a stamp when you get to the bottom of each page

P154-5

ElectromagnetismThe direction of a magnetic field outside a magnet is from north to south (that is why a compass points north)

The earth’s magnetic field is caused by currents in the earth’s core and changes over time.

All magnetic fields are produced by moving electric charges (electromagnets use electricity). The field is perpendicular to the wire. Changing the magnetic field changes both the current and the voltage.

A moving charge is deflected when it crosses magnetic field lines. This force can be used to do work. The magnetic field is strongest near the center

5. A generator converts energy into electricity. A motor turns electricity into mechanical energy.

6. Faradays law

Magnetism modelp155

NOVA: Magnetic Storm video ( north to south (that is why a compass points north)youtube) wkst

CDP 36-1

Phet: Magnetism and Electromagnets

Last chance for stamps on these wksts!

FinishSummary north to south (that is why a compass points north)Get a stamp at the end of class

How Electrical Grids work webquest1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19-31

32-49

50-70

p159

When I hit the table with the hammer, where does the energy come from? Where does it go?

When I hit 2 metal spheres together, where does the energy come from? Where does it go?

p160

It’s always about energy!What will happen when you add 1 drop of food coloring to each beaker?Record your predictionand then gently add one drop to each beaker.

P160

- Hot water
Observations:

Explanation:

- Cold water
- Observations:

p161 each beaker?

White board your group answers to share out:- What is temperature a measure of?
- How does a thermometer work?
- What temperature scales do you know?
- What is absolute zero?

Explain how the two cups of water are different each beaker?

Draw a picture of 10 water molecules in a cup of cold water, and then the same 10 molecules of water in a warm cup of water (same size cup!)

p162

1. Measures the movement (speed) of molecules (more energy=more speed)

2. As the molecule speed increases, the molecules spread out taking up more space. This is what happens in a thermometer.

3. Centigrade (celsius), kelvin, farhenheit

4. Absolute zero is when molecules stop moving and therefore take up zero space (impossible!)

p163

Temperature model driving question: what does temperature really measure?What do you SEE in the cartoon? energy=more speed)

Use what you see, and your prior experience to answer the questions What Do You Think in your notebook

As you add cold milk to hot coffee, you expect that the milk will get warmer, and the coffee will get a bit colder. What determines the final temperature of the coffee and the milk?

Section 7: Laws of Thermodynamics (p664-677)p164

What happens if you mix 50ml of water at 50 energy=more speed)oC and 50ml of water at 100oC?

Explain:

Try it! Heat Mixes Lab (part 1)

Steps 1-4 equal amounts of hot/cold

Steps 5-7 2/3 hot:1/3 cold

Steps 8-9 1/3 hot:2/3 cold

Heat Mixes Lab (part 2)

Steps 1-6 equal amounts hot nails: cold water

Steps 7-11 equal amounts cold nails: hot water

Was your prediction correct?

P164

Mixologist- Steps 1-4 equal amounts of hot/cold energy=more speed)
Hot 53.5C: cold 3.4C final 29C

- Steps 5-7 2/3 hot:1/3 cold
Hot 45.5C: cold 4.0C final 29C

- Steps 8-9 1/3 hot:2/3 cold
Hot 48.3C: cold 4.5C final 19.9C

Heat Mixes Lab (part 2)

- Steps 1-6 equal amounts hot nails: cold water
Hot 37.7C: cold 21.1C final 22.8C

- Steps 7-11 equal amounts cold nails: hot water
Hot 48.2C: cold 3.7 final 43.5C

Describe at least two ways that students made predictions. The evidence supported which method?

Equal amounts of hot water (80oC) are added to cold water (10oC). Explain how to predict the final temperature (and then do the math!)

Students performed the experiment, but only measured a final temp of 40oC Where did the extra heat go?

Predict the final temp of 3 parts 30oC and 1 part 70oC water.

Did adding equal amounts of metal nails have the same effect as adding equal amounts of water? What does this say about heating metal compared to heating water?

Get a stamp when finished

P165

Follow the directions The evidence supported which method?on the handout.

Answer all the questions and make the graph in your notebook using a graph stamp.

Get your notebook stamped when you are finished.

CU (p672) 1-4

CDP 21-1

Investigationp165

5 The evidence supported which method?. Temperature is a measure of the average kinetic energy of the particles that make up the object.

6. The specific heat of a material is a measure of how much energy is required to heat 1 gram of material 1 degree celcius.

7. Two objects in contact will reach the same temperature (equilibrium)

8. 1stLaw of thermodynamics: heat = energy + work

9. 2nd Law: Heat is a form of energy and can be transformed from a warmer object to a cooler object. Heat always flows from warmer to colder

10. entropy = disorder when heat flows from warmer to colder entropy (disorder) increases

Energy Model: Section 7DQ: what is enegy and how is it transferred?p163

11 The evidence supported which method?. A conductor allows heat to flow easily. An insulator traps heat and does not allow it to flow.

12. Heat energy (Q) is measured by multiplying the mass (in grams) times the temperature change times a specific heat constant (the constant for water is 1 g/C/cal or 4.17 g/C/Joule)

Q=m(Tf-Ti)c

p163

Energy Model/PtoGo (p676-677) 1-9Hot nails 37.7C: cold water 21.1C final 22.8C The evidence supported which method?

- How much heat was lost by the nails?
Q=m(Tf-Ti)c massnails=41g csteel=0.12 g/C/cal

- Where did that heat go?
- How much heat was gained by the water?
Q=m(Tf-Ti)c masswater=41g cwater=1.00 g/C/cal

p168

Heat Mixes Lab (part 2) revisitedEnergy is transferred by direct contact The evidence supported which method?

Give an example:

p168

conductionEnergy is transferred by the mass motion of molecules The evidence supported which method?

Give an example:

p168

convectionEnergy is transferred by electromagnetic radiation The evidence supported which method?

Give an example:

p168

radiationThe Drinking Bird Lab The evidence supported which method?

So what makes the bird drink?

Video

Video explanation

What NOT to do!

Answer all the questions

Get a stamp when you finish

Energy transfer processesp169

Using only your hands, find the coldest substance around you The evidence supported which method?…

How can we remove enough heat to make ice cream?

Video

Follow the directions or your ice cream will not turn out! Get a stamp when you are cleaned up.

Answer all the questions and get another stamp.

We all scream for ice cream!p171

- Draw 6 water molecules in each box (remember molecules are always the same size, only the spacing is different
- Make a statement about the density of water molecules in each phase

p169

Does it take energy to melt ice?

Whiteboard time… always the same size, only the spacing is different

- Make a line graph to show the temperature vs the heat energy of water. Include these words: solid ice, liquid, water vapor(steam), melting, freezing, boiling, condensing

T

E

M

P

E

R

A

T

U

R

E

HEAT ENERGY

Phase changes of water diagram always the same size, only the spacing is different(white book p459)

p169

Finish

CDP 23-1

23-2

Solving problems always the same size, only the spacing is different

1.) How much heat is required

to melt 5 grams of ice?

2.) How much heat is required

to heat 45 g of ice water to 60C?

3.) How much heat is required by your stomach melt 15 grams of ice and raise the water temperature to 40C?

p170

Does the water change temperature? If yes….Q=mc

If no…..Q=mΔTc

Answers always the same size, only the spacing is different

1.) How much heat is required to melt 5 grams of ice?

(5 grams)(80 cal/gram) = 400 Cal

2.) How much heat is required to heat 45 g of water?

(45 grams)(60)(1 cal/gram/degree) = 2700 cal

3.) How much heat is required by your stomach melt 15 grams of ice and raise the water temperature to 40C?

(15)(80) = 1200 cal

(15)(1)(40) = 600 cal

total = 1800 calories

What do you SEE in the cartoon? always the same size, only the spacing is different

Use what you see, and your prior experience to answer the questions What Do You Think in your notebook

What do we use hot water for?

Most American homes use more energy to heat water than all the other energy uses combined. There are 2 main types of water heaters. A big tank of water that is heated by a gas flame (and kept hot until you want to use it) and “instant” water heaters that use electricity through an immersion unit to heat water only when you want to use it.

Which type do you have at home?

Which do you think is more efficient?

p173

Section 8: Energy Consumption (p678-680)Assemble a calorimeter using two always the same size, only the spacing is differentstyrofoam cups on the base and another as a lid (making holes in the lid for the thermometer and the immersion heater. Follow the directions in the book (p679-680)

Make the water at least 25 degrees hotter before you stop

Answer all the questions and calculations in your notebook

Get your notebook stamped when you are finished.

Investigation (do all steps 1-5)p173

13. always the same size, only the spacing is differentEfficiency of a system = useful energy output/total energy supplied

14. Electrical energy E = Pt = VIt

15. Electrical energy is measured in kilowatt-hours

16. 1st Law of Thermodynamics. Energy is conserved. Energy can be transferred, but is neither created or destroyed

Energy Model: Section 8p163

How much energy do you use? always the same size, only the spacing is different

Follow the directions on the handout. Do all work in your notebook. The SMUD handouts stay in this room!

Get a stamp when finished

CU p682) 1-4 Get stamped when finished (you do not have to do the PtoGo questions on the back…you already did them!)

Energy Consumption (PtoGo p686)P174-5

Rank the 3 appliances from most efficient to least efficient.

Rank the 3 appliances from greatest cost to heat 1 beaker of water to least cost.

If high-efficiency appliances cost more, are they worth the extra cost?

Section 9: Comparing Energy Consumption (p691-698)p176

Heat Coil Hot Plate Microwave

p176 efficient.

Which appliance is most efficient?1.) Copy the chart into your notebook.2.) Do you want to change any of your predictions? Give a reason!

3.) Calculate the heat energy for each beaker of water.

4.) Calculate the energy given off by each appliance.

5.) Calculate the efficiency of each appliance.

6.) Which appliance was most efficient?

7.) Assume energy costs $10.40 cents per watt-s and calculate the cost for each appliance to heat the same beaker of water. Does this surprise you?

Follow the directions in the book (p691-693) efficient.

Answer all the questions and do the calculations in your notebook.

Get your notebook stamped when you are finished.

CU (p695) 1-6

PtoGo (p698) 1-9

investigationP176-7

17. efficient.Heat may be transferred by conduction, convection, or radiation. Conduction occurs when two objects are touching each other. Convection occurs through the movement of a fluid. Radiation occurs when the warmer object emits electromagnetic waves in all directions and the cooler object absorbs some or all of it

18. 2nd Law of Thermodynamics. Heat flows from hot to cold, increasing the disorder by making molecules move faster (entropy).

19. 3rd Law of Thermodynamics. We can never reach absolute zero because it is impossible for molecules to stop moving.

p163

Energy model: Section 9Study your quizzes (Electricity and Heat) efficient.

Study your purple model sheets

Practice by playing jeopardy (on my website)

Unit Test Friday!House project efficient.

- Build a scale model house
- Compare energy costs and present on a poster
- Wire your house with simple circuits and light bulbs

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