Download here - electriccircuits

Rutchelle Enriquez and Kevin McReynolds
Technology-enhanced science unit:
TARGET POPULATION: 8TH GRADE MIDDLE SCHOOL PHYSICAL SCIENCE.
GOALS RELATING TO THE GEORGIA PERFORMANCE STANDARDS
S8CS5 Students will use the ideas of system, model, change, and scale in exploring scientific and
technological matters.
a. Observe and explain how parts can be related to other parts in a system.
b. Understand that different models (such as physical replicas, pictures, and analogies) can be used to
represent the same thing.
S8CS9 Students will understand the features of the process of scientific inquiry.
b. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and
formulating explanations to make sense of collected evidence.
c. Scientific experiments investigate the effect of one variable on another. All other variables are kept
constant.
S8P5 Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of
forces acting in nature.
b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer
energy.
CONCEPT MAP:
DAY 1: Loads and Wires
MAIN TOPICS

Components of a Circuit

Open and Closed Circuit

Loads and Resistors

Energy Transformation
PEDAGOGICAL OVERVIEW: THIS UNIT PROVIDES STUDENTS
OPPORTUNITIES TO USE COMPUTER RESOURCES, TRADITIONAL
EXPERIMENTAL TECHNOLOGIES, AND SOME INNOVATIVE
METHODOLOGIES TO EXPLORE THE THREE COMPONENTS OF
SIMPLE ELECTRIC CIRCUITS: LOADS, CONDUCTORS, AND
BATTERIES. STUDENTS ARE CHALLENGED TO INVESTIGATE
USING GUIDED INQUIRY AND ARE ENCOURAGED TO EXTEND
THEIR THINKING WITH REAL-WORLD SCENARIOS.
ACTIVITIES
1.
Students will make a bulb light using one bulb, one battery and one wire
Students will sketch circuits that make the light work and those that do not.
Ask students to orally identify common types of loads and the kind of energy transformation
they do:
Electrical to radiant (light): light bulb, flashlight, TV, etc.
Electrical to mechanical: toys, electric fan, blender, electric car, radio, etc.
Electrical to thermal (heat): electric stove, heater,
iron, etc.
2.
Simulation of Conductors and Insulators
PEDAGOGY: students will manipulate computer
models to develop an intuitive sense of the role
of insulators and conductors
Students will use the PhET simulation at
http://phet.colorado.edu/simulations/sims.php?sim=Circuit_Construction_Kit_DC_Only and
respond to a guided-inquiry worksheet (1). Discussion will follow.
3. Students will answer a quiz online using http://www.surveymonkey.com/s/MGLYBVC
DAY 2: Batteries
MAIN TOPICS


Circuit Symbols
Chemical Reaction in the Battery
PEDAGOGY: students use unique objects and methods to develop
an understanding of how batteries produce electric current. the
function of an led is also investigated. students are asked to
expand their findings and draw conclusions about the direction of
electric current from different metal combinations.
ACTIVITY
Students will perform The Lemon Battery Activity using the LabMaster voltmeter and respond
to a guided-inquiry worksheet (2). Discussion will follow.
DAY 3: The Complete Circuit.
MAIN TOPICS

Measuring Voltage and Current using
Voltmeter and Ammeter

Series and Parallel Circuits
PEDAGOGY: students will construct virtual series
and parallel circuits to be compared (later) to
circuits with actual materials. Their comparisons
will be discussed in an open forum discussion at
the end of this lesson
ACTIVITIES
1.
Students will use the simulation at
http://phet.colorado.edu/simulations/sims.php?saim=Circuit_Construction_Kit_DC_Only
then respond to a guided-inquiry worksheet (3)
2.
Watch a video of the operation of voltmeter and ammeter at
http://www.youtube.com/watch?v=LgPOa1b5LgM
3.
Construction of Real Circuits using wires, bulbs, 1.5 V batteries and data collection (see
worksheet 4).
4.
Discussion of the differences/similarities between PhET data and “real” data. Oral
debriefing using guiding questions from the teacher. (see Discussion Guide)
DAY 4: Inside the Resistor and Ohm’s Law
MAIN TOPICS


The Resistor
Ohm’s law: V=IR
PEDAGOGY: Students will investigate the way a resistor
functions and manipulate the variables in ohm’s law. this
activity will help students develop the concepts of direct
and inverse relationships.
ACTIVITIES
1. PhET simulation of the resistor at
http://phet.colorado.edu/simulations/sims.php?sim=BatteryResistor_Circuit and worksheet (5)
2. PhET simulation for Ohm’s law at
http://phet.colorado.edu/simulations/sims.php?sim=Ohms_Law and worksheet (5)
3. Discussion will follow as prescribed in the worksheet.
4. Hangman game for vocabulary: http://education.jlab.org/vocabhangman/index.html
UNIT ASSESSMENT:
In order to check the understanding of students on the entire unit, they will be given the
Unit Assessment on Electric Circuits.
Worksheet 1
Conductors and Insulators
Learning Goals:



Students will understand basic properties of circuits.
Students will understand what is required to complete a circuit.
Students will learn about conductors and insulators.
Open the PhET simulator at
http://phet.colorado.edu/simulations/sims.php?sim=Circuit_Construction_Kit_DC_Only
Open the DC only circuit simulator
A. Find a way to make a single light bulb light up with as FEW parts hooked up as possible.
When electricity flows through wires and makes something work, like a light bulb, it is called a
circuit.
1. Sketch your circuit below:
2. What seems to be making the light bulb turn on in your circuit? (what do you notice is
“traveling” around)
B. Make a gap in your circuit.
Go to the grab bag and play with the different objects. Find out which objects allow electricity
to flow and fill in the data table:
Objects that allow electricity to flow
(conductors)
Objects that do NOT allow electricity to
flow (insulators)
3. What do the conductors have in common?
4. What do the insulators have in common?
Worksheet 2
The Lemon Battery
Essential Question: What does it take to create electricity?
Materials
Variety of metal strips (magnesium, copper, aluminum, iron nail, zinc)
Lemon (also pickle, orange, potato)
LED (low voltage)
Two clip leads
Voltage probe
Part 1: Making Light - Initial Inquiry
You have several materials in front of you. Use your lemon, some
metal strips, connecting wires and the LED to
make the LED light up.
The picture at the right is a magnified view of an
LED.
[note: An LED is a device that conducts
electricity in only one direction. Look carefully at the LED. You should be
able to locate one wire that is slightly longer than the other. This longer wire
is the positive terminal.]
Keep a good RECORD of what you are doing. In the space below describe what happened.
WHAT DID YOU NOTICE?
Try hooking up the LED “forwards” and “backwards.” Does it work both
ways?
As you work with your battery and LED keep a record of when the light
turns on. Record this information in the table below. Try using different
metals as electrodes. Record your information in the table below?
TABLE 1
Metal on left
Metal on right
Turns on?
Yes or NO
Copper
Magnesium
Magnesium
Copper
Copper
Iron
Iron
Copper
Copper
Zinc
Zinc
Copper
Try using electrodes of the same metals. What do you notice?
Metal that must
be attached to
the positive
terminal
Part 2: Measuring the Voltage – Structured Inquiry
Remove the LED for now.
Connect the voltage probe to your metals strips and measure the voltage developed by your
lemon battery. A few suggestions are listed, and then you make decisions about the setup.
Indicate the changes you make and the resulting voltages of your battery. Think carefully about
the metal that must be attached to the positive terminal and note when that metal is attached to
the red wire for the voltage probe.
RECORD your findings in the table below.
TABLE 2
Describe the Setup
Resulting Voltage
Notes / Comments
Copper electrode
Magnesium electrode
Copper electrode
Iron (nail) electrode
Copper electrode
Zinc electrode
Double up the electrodes
WHAT DID YOU NOTICE?
Compare your findings with a neighboring group. Indicate any differences between your
findings in the Notes / Comments column.
Sometimes you might have gotten a negative value for voltage. Make a connection between the
way the metals were attached to the meter AND you information from TABLE 1 to draw a
conclusion about why the negative value occurred.
From what you have done, what do you think determines the amount of voltage developed by a
battery?
Try making a voltage without using the lemon. RECORD what you did in the space below and
indicate what you found out.
Questions and Analysis
Directions: Answer each of these based on the experiment you performed today.
1.
Does the electricity come from inside the lemon or from an interaction between the
lemon juice and the metals?
2.
Did you notice any indication of chemical activity (bubbling, smoking, getting hot or
cold, etc.) during your experimentation? What can you infer from this?
3.
A battery is one key piece in an electrical circuit. Draw and label the following from
your experiment: voltage source, conducting wires, load.
4.
5.
On this picture of our lemon battery draw the
directions electrons must travel. Use arrows to
indicate how electrons travel to the negative post from
the lemon and from the positive post into the lemon.
Note the red and black colors on the wires – remember
what those indicated on the voltmeter.
If you had to explain the operation of a battery to a much younger person (3rd grader),
what would you say?
Worksheet 2
The Lemon Battery
Possible responses and/or teacher resource information in RED
Essential Question: What does it take to create electricity?
Materials
Variety of metal strips (magnesium, copper, aluminum, iron nail, zinc)
Lemon (also pickle, orange, potato)
LED (low voltage)
Two clip leads
Voltage probe
Part 1: Making Light - Initial Inquiry
You have several materials in front of you. Use your lemon, some
metal strips, connecting wires and the LED to
make the LED light up.
The picture at the right is a magnified view of an
LED.
[note: An LED is a device that conducts
electricity in only one direction. Look carefully at the LED. You should be
able to locate one wire that is slightly longer than the other. This longer wire
is the positive terminal.]
Keep a good RECORD of what you are doing. In the space below describe what happened.
When the copper is attached to the positive terminal the LED lights up. Other metals may also
cause the LED to light, but reversing the metals to the other terminal will not light the LED.
WHAT DID YOU NOTICE?
Try hooking up the LED “forwards” and “backwards.” Does it work both
ways? It does not work both ways
As you work with your battery and LED keep a record of when the light
turns on. Record this information in the table below. Try using different
metals as electrodes. Record your information in the table below?
TABLE 1
Metal on left
Metal on right
Turns on?
Yes or NO
Metal that must
be attached to
the positive
terminal
Copper
Magnesium
Copper
Magnesium
Copper
Copper
Copper
Iron
copper
Iron
Copper
copper
Copper
Zinc
Copper
Zinc
Copper
Copper
Try using electrodes of the same metals. What do you notice?
When electrodes of the same metal are used the LED does not light up
Part 2: Measuring the Voltage – Structured Inquiry
Remove the LED for now.
Connect the voltage probe to your metals strips and measure the voltage developed by your
lemon battery. A few suggestions are listed, and then you make decisions about the setup.
Indicate the changes you make and the resulting voltages of your battery. Think carefully about
the metal that must be attached to the positive terminal and note when that metal is attached to
the red wire for the voltage probe.
RECORD your findings in the table below.
TABLE 2
Describe the Setup
Resulting Voltage
Notes / Comments
Copper electrode
Magnesium electrode
Approx 3 V
Copper electrode
Iron (nail) electrode
Approx 1 V
Copper electrode
Zinc electrode
Approx 1 V
Double up the electrodes
Voltage does not increase a
great deal, if at all
The LED glows brighter –
due to lowered resistance of
parallel conductors
WHAT DID YOU NOTICE?
Compare your findings with a neighboring group. Indicate any differences between your
findings in the Notes / Comments column.
Sometimes you might have gotten a negative value for voltage. Make a connection between the
way the metals were attached to the meter AND you information from TABLE 1 to draw a
conclusion about why the negative value occurred. Specific connections yield + voltage, if
reversed the voltage becomes negative
From what you have done, what do you think determines the amount of voltage developed by a
battery? Voltage is determined by the chemistry of the metals involved
Try making a voltage without using the lemon. RECORD what you did in the space below and
indicate what you found out. May get voltage developed if there is an electrolyte solution
Questions and Analysis
Directions: Answer each of these based on the experiment you performed today.
5.
Does the electricity come from inside the lemon or from an interaction between the
lemon juice and the metals? Comes from interaction between lemon juice and the
metals
6.
Did you notice any indication of chemical activity (bubbling, smoking, getting hot or
cold, etc.) during your experimentation? What can you infer from this? May see
some bubbling at the site of the magnesium metal
7.
A battery is one key piece in an electrical circuit. Draw and label the following from
your experiment: voltage source, conducting wires, load.
8.
On this picture of our lemon battery draw the
directions electrons must travel. Use arrows to
indicate how electrons travel to the negative post from
the lemon and from the positive post into the lemon.
Note the red and black colors on the wires – remember
what those indicated on the voltmeter.
should indicate electrons leaving the magnesium (silvery)
terminal traveling through the LED and into the copper (reddish)
terminal then into the lemon pulp
5.
If you had to explain the operation of a battery to a much younger person (3rd grader),
what would you say? Answers will vary
Worksheet 3
Series and Parallel Circuits
Learning Goal

Students will be able to build series and parallel circuits and understand the difference
between the different circuits.
Open the PhET site:
http://phet.colorado.edu/simulations/sims.php?sim=Circuit_Construction_Kit_DC_Only
For the next few activities, you need to light up more than 1 bulb at the same time, using just one
battery.
First circuit: find a way to hook up your bulbs in a way that if you break the connection at one
bulb, ALL bulbs go out.
1
Sketch your new circuit:
2. Why did the rest of the bulbs go out if you break the connection at one bulb?
3. This circuit is called a series circuit because the bulbs are hooked up in one long “series”
or line. Name somewhere you have seen a string of lights that are also a series circuit.
Second circuit: find a way to hook up your bulbs in a way that if you break the connection at one
bulb, ONLY that bulb goes out.
4. Sketch this circuit:
5. Why do the rest of the bulbs stay lit if you break the connection at one bulb?
6. This circuit is called a parallel circuit, which has 2 or more single loops connected to the
same battery. When 1 bulb goes out in these circuits, the rest of the lights stay on! Name
somewhere you have seen many bulbs hooked up to one power source, where one bulb
can go out without affecting the others.
7. You design toys for a toy company. Your boss wants you to hook up the lights in the toy
car you are working on in the cheapest way possible, without consideration of the quality
of the toy. Which circuit should you use if you want to save money by using fewer parts?
Why would this circuit be cheaper?
8. You are an electrician working on a house. What type of circuit should you use for the
house so that the owners don’t call to complain about their wiring? Why use this circuit?
Experiment with the simulator, see what you can make it do!!!
9. What did you do to make light bulbs glow brighter?
10. What did you do to make light bulbs glow dimmer?
11. How can you cause a fire? (In the simulator… NOT in the real world!)
12. Can you catch the puppy on fire? (JUST KIDDING!)
Worksheet 3
Series and Parallel Circuits
Learning Goal

Students will be able to build series and parallel circuits and understand the difference
between the different circuits.
Open the PhET site:
http://phet.colorado.edu/simulations/sims.php?sim=Circuit_Construction_Kit_DC_Only
For the next few activities, you need to light up more than 1 bulb at the same time, using just one
battery.
First circuit: find a way to hook up your bulbs in a way that if you break the connection at one
bulb, ALL bulbs go out.
1
Sketch your new circuit: should indicate a series circuit
2. Why did the rest of the bulbs go out if you break the connection at one bulb?
Open circuit breaks the flow of electrons
3. This circuit is called a series circuit because the bulbs are hooked up in one long “series”
or line. Name somewhere you have seen a string of lights that are also a series circuit.
Answers will vary – because most light strings (except for inexpensive holiday lights) are
wired in parallel don’t be surprised if this is difficult for students – use this difficulty to lead
into the next topic.
Second circuit: find a way to hook up your bulbs in a way that if you break the connection at one
bulb, ONLY that bulb goes out.
13. Sketch this circuit: should indicate a parallel circuit
14. Why do the rest of the bulbs stay lit if you break the connection at one bulb?
An alternative path for electron flow still exists
15. This circuit is called a parallel circuit, which has 2 or more single loops connected to the
same battery. When 1 bulb goes out in these circuits, the rest of the lights stay on! Name
somewhere you have seen many bulbs hooked up to one power source, where one bulb
can go out without affecting the others. Most light “strings” are wired this way as are the
lights in the classroom – if you can reach the overhead bulbs, take one out and
demonstrate that the others stay on.
16. You design toys for a toy company. Your boss wants you to hook up the lights in the toy
car you are working on in the cheapest way possible, without consideration of the quality
of the toy. Which circuit should you use if you want to save money by using fewer parts?
Why would this circuit be cheaper? Series usually requires fewer wires
17. You are an electrician working on a house. What type of circuit should you use for the
house so that the owners don’t call to complain about their wiring? Why use this circuit?
Parallel – so that when one goes out the others do not go out.
Experiment with the simulator, see what you can make it do!!!
18. What did you do to make light bulbs glow brighter?
May indicate they decreased the number in series, or increased the branched in parallel
19. What did you do to make light bulbs glow dimmer? Opposite of above
20. How can you cause a fire? (In the simulator… NOT in the real world!)
Too much current creates heat
21. Can you catch the puppy on fire? (JUST KIDDING!)
Worksheet 4
Series and Parallel Circuits using bulbs, batteries, wires and meters
Engage: Show students two different strings of holiday lights: one strand has lights that go out
when one light bulb is removed and another has lights that stay on when one bulb is removed.
Students will be given:
1.5-V batteries, several holiday lights (recycled and cut from and old strand), conducting wires
with alligator clip ends
Explore:
1.
2.
3.
4.
5.
6.
Connect your bulbs to the batteries so that when one bulb is disconnected the whole
strand of lights goes out. This is a series circuit.
Draw your circuit by using standard symbols.
Use your voltmeter to measure the voltage of the batteries. RECORD
Use your voltmeter to measure the voltage across each bulb. RECORD
What do you notice about the total voltage from the battery compared to the sum of
the voltages from each bulb?
Now use your ammeter to measure the current going through each bulb. RECORD.
SERIES CIRCUIT
Voltage
Batteries
Bulb 1
Bulb 2
Bulb 3
Current
7.
8.
Connect your bulbs to the batteries so that when one bulb is disconnected the whole
strand of lights does NOT go out. This is a parallel circuit.
Draw your circuit by using standard symbols.
9.
10.
11.
Use your voltmeter to measure the voltage of the batteries. RECORD
Use your voltmeter to measure the voltage across each bulb. RECORD
Now use your ammeter to measure the current across each bulb. RECORD
PARALLEL CIRCUIT
Voltage
Current
Batteries
Bulb 1
Bulb 2
Bulb 3
EXTEND and ELABORATE
1.
In our classroom explain whether the lights are connected in series or in parallel.
How do you know?
2.
Which type of holiday lights would you rather purchase: series lights or parallel
lights? Why?
3.
Return to your experiment with the bulb, batteries and wires. Starting with one bulb,
add more bulbs and describe what happens to the brightness as you add additional
bulbs in series.
4
With the bulbs, batteries and wires start with one bulb and add more bulbs in parallel.
Describe what happens to the brightness as you add additional bulbs.
Discussion Guide – the differences between the real world circuits and the circuit simulations
1.
For you, what were the best parts of using the computer simulation?
2.
Which setup (real vs. computer) allowed you to make changes in your circuit easier?
3.
Which setup (real vs. computer) would be better to use if you were about to wire a house?
4.
What differences did you notice between the outcomes of the two setups?
5.
What recommendations would you make to someone using each of these setups next
year?
Worksheet 4
See possible student responses in RED
Series and Parallel Circuits using bulbs, batteries, wires and meters
Engage: Show students two different strings of holiday lights: one strand has lights that go out
when one light bulb is removed and another has lights that stay on when one bulb is removed.
Students will be given:
1.5-V batteries, several holiday lights (recycled and cut from and old strand), conducting wires
with alligator clip ends
Explore:
12.
13.
14.
15.
16.
17.
Connect your bulbs to the batteries so that when one bulb is disconnected the whole
strand of lights goes out. This is a series circuit.
Draw your circuit by using standard symbols.
Use your voltmeter to measure the voltage of the batteries. RECORD
Use your voltmeter to measure the voltage across each bulb. RECORD
What do you notice about the total voltage from the battery compared to the sum of
the voltages from each bulb?
Now use your ammeter to measure the current going through each bulb. RECORD.
SERIES CIRCUIT
Voltage
Batteries
Bulb 1
Bulb 2
Bulb 3
Current
18.
19.
Connect your bulbs to the batteries so that when one bulb is disconnected the whole
strand of lights does NOT go out. This is a parallel circuit.
Draw your circuit by using standard symbols.
20.
21.
22.
Use your voltmeter to measure the voltage of the batteries. RECORD
Use your voltmeter to measure the voltage across each bulb. RECORD
Now use your ammeter to measure the current across each bulb. RECORD
PARALLEL CIRCUIT
Voltage
Current
Batteries
Bulb 1
Bulb 2
Bulb 3
EXTEND and ELABORATE
4.
In our classroom explain whether the lights are connected in series or in parallel.
How do you know?
Should indicate “parallel” because one can go out but this does not affect the others
5.
Which type of holiday lights would you rather purchase: series lights or parallel
lights? Why? May say “series” because of lowered cost, may indicate “parallel”
because of the tendency of the other lights to stay lit.
6.
Return to your experiment with the bulb, batteries and wires. Starting with one bulb,
add more bulbs and describe what happens to the brightness as you add additional
bulbs in series. Addition of more bulbs causes them to get dimmer
7.
With the bulbs, batteries and wires start with one bulb and add more bulbs in parallel.
Describe what happens to the brightness as you add additional bulbs.
Addition of more bulbs causes them to get brighter
Worksheet 5
Inside of a Resistor and Ohm’s Law Simulations
Essential Questions:
1. How does resistance resist current?
2. How are current, voltage and resistance related?
Tasks:
Part I: Inside of a Resistor
Open this site:
http://phet.colorado.edu/simulations/sims.php?sim=BatteryResistor_Circuit
1. Before playing with the arrow bars, describe what you see on the screen. What do the green
balls represent? How about the blue balls? Can you identify the units of these variables you see?
List them down.
2. Now you can adjust the resistance arrow bar.
2.1 How is the speed of the blue particles affected by the increase or decrease in resistance? How
is the temperature affected by these changes?
2.2 If the resistor was a filament of a bulb, how would its temperature relate to its brightness?
Part II: Ohm’s Law
Open this site:
http://phet.colorado.edu/simulations/sims.php?sim=Ohms_Law
1. Before playing with the buttons, describe what you see on the screen. Can you identify the
units of these variables? If yes, list them down.
2. Now you can adjust the buttons.
2.1 How does the increase and decrease of voltage affect current and resistance?
2.2 How does the increase and decrease of resistance affect current and voltage?
2.3 Did you have to change all three variables to see differences in any of the three? Describe
what happens when you adjust a button.
3.0 Explain how current, voltage and resistance are related.
4.0 Prepare to share your answers with the class.
Worksheet 5 – Expected Student Responses
Worksheet for Inside of a Resistor and Ohm’s Law Simulations
Expected student responses are indicated in RED.
Essential Questions:
1. How does resistance resist current?
2. How are current, voltage and resistance related?
Tasks:
Part I: Inside of a Resistor
Open this site:
http://phet.colorado.edu/simulations/sims.php?sim=BatteryResistor_Circuit
1. Before playing with the arrow bars, describe what you see on the screen. What do the green
balls represent? How about the blue balls? Can you identify the units of these variables you see?
List them down.
The green balls represent the ability of the resistor to block the blue balls from flowing.
The blue balls are the electrons. There is an ammeter with a wind vane. There is a battery. There
are resistance button, voltage button and a temperature color chart with arrow. The unit of
resistance is ohm, current is ampere, voltage is volts, temperature is Celcius.
2. Now you can adjust the resistance arrow bar.
2.1 How is the speed of the blue particles affected by the increase in resistance?
When resistance is increased by adjusting the arrow to the right, many greens balls
appear. The blue balls are then slowed down.
2.2 How is the speed of the blue particles affected by the decrease in resistance?
When resistance is decreased by adjusting the arrow to the left, the green balls lessen so
the blue balls are able to move fast.
2.3 How is the temperature affected by these changes?
The temperature becomes hot when the blue balls move fast.
2.4 If the resistor was a filament of a bulb, how would its temperature relate to its brightness?
The filament will become really hot and glow brightly.
Part II: Ohm’s Law
Open this site:
http://phet.colorado.edu/simulations/sims.php?sim=Ohms_Law
1. Before playing with the buttons, describe what you see on the screen. Can you identify the
units of these variables? If yes, list them down.
There are buttons for voltage and resistance. You can also see their values on top of the
adjustable buttons. There is a circuit with three batteries and a resistor. There is also a drawing of
an equation V=IR. The unit of resistance is ohm, current is ampere, and voltage is volts.
2. Now you can adjust the buttons.
2.1 How does the increase in voltage affect current?
When voltage is increased, current is also increased.
2.2 How does the decrease in voltage affect current?
When the voltage is decreased, current is also decreased.
2.3 How does the increase in voltage affect resistance?
When voltage is increased, nothing happens to resistance.
2.4 How does the decrease in voltage affect resistance?
When voltage is decreased, nothing happens to resistance.
2.5 How does the increase in resistance affect current?
If resistance is increased, current is decreased.
2.6 How does the decrease in resistance affect current?
If resistance is decreased, current is increased.
2.7 How does the increase in resistance affect voltage?
If resistance is increased, nothing happens to voltage.
2.8 How does the decrease in resistance affect voltage?
If resistance is decreased, nothing happens to voltage.
2.9 Was there a variable that did not change when you adjusted resistance? How about when you
adjusted voltage?
When resistance was adjusted, voltage did not change. When voltage was adjusted,
resistance did not change. Thus, when either voltage or resistance is adjusted, one variable
remains the same.
3.0 Use the words “smaller” and “bigger” to describe what happens when you make:
a) voltage bigger, what happens to current?
Current is bigger.
b) resistance bigger, what happens to current?
Current is smaller.
c) resistance bigger, what happens to voltage?
Nothing happens to voltage.
3.1 Describe the general trend you observed when you adjust the voltage button.
When voltage is increased while resistance is kept constant, current also increased. When
voltage is decreased while resistance is kept constant, current also decreased.
3.2 Describe the general trend you observed when you adjust the resistance button.
When resistance is increased while voltage is kept constant, current does the opposite. It
is decreased. When resistance is decreased while voltage is kept constant, current is increased.
4.0 Prepare to share your answers with the class.
Unit Assessment: Electric Current
Name:
Short Answer
Directions: Provide a brief, correct answer to each of the following. Each question is worth 5
points.
1.
What is electric current? How is it measured?
2.
A resistor has a value of 8.0 Ω and is connected to a battery with a voltage of 12 volts.
What current flows in this circuit?
3. Look closely at the diagram at the left and determine is
current is flowing in that circuit. Explain your answer.
4.Look closely at the diagram at the left. Circle
WILL be lit.
5. Is the circuit at the right a series or parallel
circuit? How do you know?
the bulb(s) that
6.
What effect (if any) does decreasing the resistance have on a circuit?
7.
On the picture of the LED, draw an arrow to identify the
direction current should flow.
8.
Given a battery, some wires and a light bulb, what could you do to determine if a lump of
charcoal is a conductor or an insulator?
9.
Identify each statement as true (T) or false (F).
_____ a) the positive and negative terminals of a battery must be made of the same metal.
_____ b) an LED conducts electricity in only one direction
_____ c) an ammeter measures resistance directly
_____ d) a battery produces electricity due to a chemical reaction
10.
When you add bulbs to a series circuit, what happens to the brightness of each bulb as
you add more?
Use Ohm’s Law to solve these problems:
11.
V = 6.0 v
I = 2.0 a,
R=?
12.
V= ?
I = 2.0 a
R = 9.0 Ω
13.
V = 6.0 v
I= ?
R = 3.0 Ω
14.
Think back on all the activities and computer resources we used in this unit. Which of
the activities do you feel have the most importance to you life? Why do you think so?
Unit Assessment: Electric Current
Student responses in RED
Name:
Short Answer
Directions: Provide a brief, correct answer to each of the following. Each question is worth 5
points.
1.
What is electric current? How is it measured?
Electric current is the flow of electrons it is measured in amperes (with an ammeter)
2.
A resistor has a value of 8.0 Ω and is connected to a battery with a voltage of 12 volts.
What current flows in this circuit?
I = V / R = 12 V / 8 Ω = 1.5 A
3. Look closely at the diagram at the left and determine is
current is flowing in that circuit. Explain your answer.
No current is flowing the circuit does not have a complete path – the
path is interrupted.
4.Look closely at the diagram at the left. Circle the bulb(s) that
WILL be lit. the two bulbs to the right will remain lit.
5. Is the circuit at the right a series or parallel circuit? How do you
know? This is a series circuit because it has only one complete current
path
6.
What effect (if any) does decreasing the resistance have on a circuit?
Decreasing the total resistance on a circuit will increase the current in the circuit
7.
On the picture of the LED, draw an arrow to identify the
direction current should flow. Current will flow into the “short” side and
out the “long” side
8.
Given a battery, some wires and a light bulb, what could you do to determine if a lump of
charcoal is a conductor or an insulator? Connect all materials in series and see if the bulb
lights up. If so then charcoal is a conductor.
9.
Identify each statement as true (T) or false (F).
__F__ a) the positive and negative terminals of a battery must be made of the same metal.
__T__ b) an LED conducts electricity in only one direction
___F_ c) an ammeter measures resistance directly
__T__ d) a battery produces electricity due to a chemical reaction
10.
When you add bulbs to a series circuit, what happens to the brightness of each bulb as
you add more? When you add more bulbs the brightness from each bulb decreases
because resistance is increased – this causes a decrease in current (and brightness)