unit 4: electricity for everyone. essential questions what is electricity and how is it measured?...

Unit 4: Electricity for Everyone

Essential Questions

• What is electricity and how is it measured?

• How do generators work?

• How is energy converted from one form to another?

• What are parallel and series circuits?

• What is a load limit, and how is it calculated?

• What does electricity cost?

Chapter Challenge

• For this unit’s chapter challenge, you will be using the scenario on page 444-445

• This is what your final exam will be in December

• A rubric will be given to you beforehand, so you know the criteria you will be assessed on

• You may prepare for the chapter challenge, but you can not bring any of your written work to the exam, only your textbook and rubric

Day 1: Generate (60 minutes)

• Learning Objectives• To understand how energy is transformed• Develop a personal model for electricity

Starter

• What are different ways that you use electricity in your daily life?

• Is there any “free” electricity available? Why pay for it if it is free?

• Time: 10 minutes

Activity 1

• Watch the following video and think of the following:• How would the light bulb not light?• What are the effects of changing the speed or

direction of cranking the generator?

• Time:

Activity 2

• You will be given a number which represents the group you are in

• You will research with your group and present what you find in a particular way

1. Powerpoint

2. Poster

3. Poem/Story/Comic strip

What to research?

• What is a generator?

• How does it work?

• What are the different types of generators?

• How is energy transformed using a generator?


• Presentations – next class

Closing and Homework

• Physics to Go, pg. 449 #2, 3, 4, 6

Day 2: Lighten Up

• Learning Objectives:• Qualitatively describe current, resistance and

voltage• Define coulomb, ampere, volt• Compare series and parallel circuits• Recognize generator output load• Extend your personal model of electricity

Starter

• Lights were the first electric appliances for the home

• How do light bulbs work?

• How does the electricity that makes the light bulbs glow work?


Activity 1

• Present your information that you researched about generators

• Time: 15-30 minutes

Activity 2

• Draw 2 diagrams of a circuit, one in series and one in parallel. They should have • 3 light bulbs• Battery

• What are the pros and cons of each type of circuit?


Activity 3

• Set up your circuits, one at a time

• Measure the voltage using the voltmeter to see if there are any differences in voltage in the two different circuits

• Check the voltage at various points in the circuit

• Write down your findings


Activity 4

• Discuss the following questions:• What is resistance, current, and voltage?• Where is there more current and voltage – in a

series circuit or parallel circuit?• Will electricity continue to flow if the circuit is

broken in a parallel circuit? A series circuit? Why or why not? Use a diagram to help explain.



• Read “For you to Read”, pg. 452

• Physics to go, pg. 454 #1• What is resistance, current, and voltage?• Where is there more current and voltage – in a series circuit

or parallel circuit?• Will electricity continue to flow if the circuit is broken in a

parallel circuit? A series circuit? Why or why not? Use a diagram to help explain.

• Vocabulary list:• Volt• Ampere• Coulomb • Resistance• Current

Day 3: Ohm’s Law

• Learning Objectives• Calculate the resistance of an unknown

resistor given the potential drop and current• Construct a series circuit • Properly use a voltmeter and ammeter in a

series circuit• Graph the relationship between voltage and

current for a resistor that obeys Ohm’s Law

Starter

• What determines the brightness of a light bulb?

• How can a dimmer switch make the same light bulb appear dim or bright?• What is resistance, current, and voltage?• Where is there more current and voltage – in a

series circuit or parallel circuit?• Will electricity continue to flow if the circuit is

broken in a parallel circuit? A series circuit? Why or why not? Use a diagram to help explain.


Activity 1

• Read through rules on pg. 456-457

• Connect various resistors from the box to the battery source

• Measure the voltage and current for the different resistors

• What happens if you have more than 1 resistor?

• Record your data


Activity 2

• Graph the following data. What will be on the x- and y-axes? What does the slope represent?


Resistor value (Ω)

Voltage (V) Current (A)

3 1.5 0.5

3 3 1

3 4.5 1.5

10 1.5 0.15

10 3 0.30

10 4.5 0.45

15 1.5 0.1

15 3 0.2

15 4.5 0.3

Activity 3

• What is the relationship between resistance, voltage and current?

• Try to write an equation that represents the relationship

• Think: how do you calculate slope?

• Time: 5 minutes

Activity 4

• Ohm’s Law Calculations:• Example: Calculate the resistance in Ohms of

a 9V battery that carries a current of 3A.• Complete the calculations questions



• Read the “For you to read” on pg. 459

• Ohm’s Law Calculations

• Physics to go, #1, 3, 4

Day 4: Load Limit

• Learning Objectives:• Define watt, insulator, and conductor• Apply P = IV• Measure the power limit of a 120-V household

circuit• Differentiate between a fuse and a circuit

breaker• Understand the need for circuit breakers and

fuses in a home

Starter

• You have heard the term “blown a fuse” or “tripped” a circuit breaker

• What is a fuse?

• What is a circuit breaker?

• What conditions do you think make a fuse “blow” or a circuit breaker “trip”?


Activity 1• How do we calculate the load limit? This will help you in

your chapter challenge Homes for Everyone dwelling

• Power = Current x Voltage (P = IV), where power is measured in watts (W)

• Suppose you have 40 60W light bulbs plugged into a 120V circuit. What is the current flowing through the circuit?

• When a 41st light bulb is plugged in, the circuit blows. What is the load limit of the circuit?

• How many 100W light bulbs could be plugged into this circuit?


Activity 2

• Determine the load limit of 1 1.5V battery

• Determine the load limit of 2 1.5V batteries

• (To do this, you must determine the current going through the circuit)

• See how many light bulbs you can hook up to try to determine the wattage of the light bulbs


Activity 3

• Complete the sample equations.

• Formulas are on next slide


Homework

• What are power, current, voltage, and resistance and how are they calculated?

• What is a circuit breaker and a fuse?

• Read Physics Talk

• Physics to Go, pg. 469 #1, 2 (note the voltage difference here, we do not use 120V, unless the appliance is from North America), 3, 4, 5, 10, 11

Day 5: Who’s in Control (60 minutes)

• Learning Objectives:• Explain how a variety of automatic electrical

switches work• Select switches and control devices to meet

particular needs• Insert a switch in a parallel circuit to control a

particular lamp

Starter

• Many electrical switches are operated manually, and many others are automatic

• List as many different kinds of automatic switching devices as you can

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


Activity 1

• Create a circuit with 3 light bulbs in parallel

• Draw a corresponding diagram (pg. 473)

• Which alligator clip could be replaced with a switch in order to turn on and off all three bulbs?• Make a diagram and test your prediction

• Which alligator clip could be replaced with a switch if you wanted to turn the furthest bulb on and off?• Make a diagram and test your prediction

• Repeat for the middle bulb, and the closest bulb to the battery


Activity 2

• Share your diagrams and conclusions with a person from another group

• Discuss any discrepancies you have in your data

• Time: 5 minutes

Homework

• Read Physics Talk, pg. 475

• Physics to go, pg. 483 #2, 3, 4, 6, 7, 9

Day 6: Cold Shower

• Learning Objectives: • Calculate the heat gained by a sample of

water• Calculate the electrical energy dissipated by a

resistor• Recognize and quantify an ideal

mechanical/electrical equivalent of heat• Calculate the efficiency of a transformation of

electrical energy to heat• Explore the power ratings and energy

consumption levels of a variety of electrical appliances

Starter

• The entire daily energy output of a Homes For Everyone (HFE) generator would not be enough to heat water for an average American family for a day.

• If an electrical heating coil (a type of resistor) were submerged in a container of water, and if a current were to flow through the coil to make it hot, what factors would affect the temperature increase of the water? Predict how each factor affects the water temperature.


Activity 1

• Before we begin our data collection, there are some formulas we need to understand• Q = mcΔT, where Q = Heat energy, m = mass, c =

specific heat of material, ΔT = change in temperature• P = E/t, where P = power, E = energy, t = time (E=Pt)

• Calculate the heat energy for a 0.5kg sample of water that went from 20°C to 45°C. The specific heat for water is 4.180J/kg°C.

• What was the energy input needed to heat the water sample if 1500W of power were used and it took 120s to heat the water?


Activity 2

• You will heat up a 100g sample of water

• Complete the table on pg. 487

• We will not use a calorimeter, just a hotplate and a beaker

• Have the hotplate going for 5 minutes

• Repeat, this time using 250g of water

• Complete a 2nd column for your table


Activity 3

• Calculate the Q and E values for each of your samples.• Q = mcΔT• E = Pt

• You will have to get the power value from your hotplate


Activity 4

• Review rubric and assessment guidelines for chapter challenge

• Assign partners


Homework

• Read Physics Talk, pg. 489

• Physics to go, pg. 492, #1, 2, 3, 4, 5, 7, 8, 9

Day 7: Pay Up

Day 8: More for Your Money

unit 4: electricity for everyone. essential questions what is electricity and how is it measured?...

Documents

minutes slide

rubric slide

class slide

poemstorycomic strip

generators time

type of circuit

series circuits

parallel circuits