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Oct 18, 2013 (3 years and 10 months ago)

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LUIS FERNANDO LARGO
-
GUTIÉRREZ

MAGNETISM

UNIT PLAN


NJ STANDARDS



5.1.12 A. Habits of mind



5.1.12 B. Inquiry and problem solving



5.1.12 C. Safety



5.2.12 A. Cultural contributions



5.2.12 B. Historical perspectives



5.3.12 A. Numerical operations



5.3.12 C. Pa
tterns and algebra



5.3.12 D. Data analysis and probability



5.4.12 C. Technological design


WHAT STUDENTS SHOULD KNOW TO BE SUCCESSFUL



Prior to this unit students should have knowledge to be successful as it shows in the follow:



Kinematics



Newtonian Dynam
ics



Circular Motion



Electric charge: Force and Energy



Electric fields


OBJECTIVES


CONCEPTUAL GOALS

FUNDAMENTAL IDEAS THAT STUDENTS NEED TO CONSTRUCT AT THE END OF THE UNIT.

GOAL

ASSESSMENT



Be able to explain why we believe that magnetic
interactions a
re different from electrostatic
interactions.




Understand that a magnetic field interacts with
moving electrically charged particles and wires
with electric currents.




Understand the difference between sources of
magnetic field and test objects in a magnet
ic field.




Learn how to describe magnetic interactions
quantitatively.




Homework, Exam, Laboratory




Concept building, Homework, Exam, Laboratory






Concept building, Homework, Laboratory





Concept building, Homework, Laboratory



QUANTITATIVE GOALS

PHYSI
CAL QUANTITIES AND MATHEMATICAL RELATIONSHIPS THAT STUDENTS NEED TO UNDERSTAND, REPRESENT IN DIFFERENT WAYS AND BE
ABLE TO APPLY PRODUCTIVELY.



Magnetic Field
: A physical quantity
characterizes the direction and strength (magnitude o
f the magnetic field
at a point. Qualitatively, the direction of the field at that point is the direction in which the north pole of a
compass needle points at that point



Magnetic Field Lines
: Magnetic field lines represent the magnetic field created by a

magnetic field source. The
direction of the magnetic field at a point is tangent to the direction of the magnetic field lime at or near that
point. The magnitude of the field is proportional to the separation of the lines in that region, the more closely
they are spaces, the stronger the field.



Magnetic Force on a current
-
carrying wire
: the force that the
field exerts on the current
-
carrying wire is
perpendicular to both the direction of the
field and to the d
irection of the current. The magnitude of the
magnetic force F
m

that a magnetic field

exerts on a wire of length L with an electric current I flowing through
it is:
, where


is the angle between the direction
s of the field and the current. The direction of
the force is given by right hand rule # 1.



Right Hand Rule # 1


Direction of the magnetic force
: point the fingers of
your open right hand in the direction of the magnetic field. Orient your hand so that
y
our right thumb points along the direction of the current. Then the direction of the
magnetic force on the current carrying wire is the direction in which your open palm
would push perpendicular to both the direction of the current and the direction of the

field.




Magnetic force on a charged particle
: the magnitude of the force that a magnetic field exerts on a particle
with electric charge q moving at velocity
in a magnetic field
is:
, where


is the angle
between the direction of

and the direction of
. Use the right hand rule # 1 to find the direction of the force.
This time put your thumb
in the direction of the velocity instead of the direction of the electric current. The
direction of the force is perpendicular to the plane in which

and
are located. The direction of the force on a
negatively
charged particle is in the opposite direction.



Magnetic torque on a current carrying coil
: a magnetic field
can exert a torque


on a coil of wire. The
magnitude of the torque is:
, where N is the number of lo
ops in the coil, I is the electric current
in the coil, B is the magnitude of the magnetic field, A is the area of the coil, and


is the angle between the coil’s
area vector and the direction of the magnetic field.



Right Hand Rule # 2
: to find the direct
ion of the magnetic field lines caused by a
current carrying wire, imagine that you grasp the current carrying wire with your right
hand. Orient the hand so that your thumb points in the direction of the current. Your
four fingers will wrap around the wire

in the direction of the magnetic field lines.





PROCEDURAL GOALS

SPECIFIC SCIENCE SKILLS THAT STUDENTS NEED TO BUILD IN THIS UNIT AND THE SCIENTIFIC ABILITIES THAT YOU
WANT YOUR STUDENTS TO STRENGTH OR DEVELOP.

GOAL

ASSESS
MENT



Be able to analyze qualitative information and data to devise
a rule for the direction and magnitude of a magnetic force.




Be able to find the direction of a magnetic field created by a
current
-
carrying wire at any given point.




Be able to evaluate s
omebody else’s reasoning.


千䥅kT䥆䥃⁁f䥌fT䥅p



Is able to evaluate the consistency of different
representations and modify then when necessary



Is able to use representations to solve problems



Is able to decide what is to be measured and identify
independe
nt and dependent variables.



Is able to use equipment to make measurements.



Is able to identify the shortcomings in an experimental design
and suggest improvements.



Is able to identify the relationship or explanation to be tested



Is able to make a reasonabl
e judgment about the relationship


Concept building, Homework, Exam,
Laboratory




Concept building, H
omework, Exam,
Laboratory




Concept building, Homework, Exam,
Laboratory




Concept building, Homework, Exam,
Laboratory



Homework, Exam, Laboratory



Homework, Exam, Laboratory




Laboratory



Laboratory




Laboratory



Laboratory

or explanation.



Is able to identify the assumptions made in using the
mathematical procedure.



Is able to determine specifically the way in which
assumptions might affect the results.



Is able to communicate the details of a
n experimental
procedure clearly and completely.



Is able to identify sources of experimental uncertainty.



Is able to evaluate specifically how experimental uncertainties
may affect the data.




Laboratory, Homework




Laboratory




Lab
oratory




Laboratory



Laboratory



EPISTEMOLOGICAL GOALS

UNDERSTANDING OF THE CONSTRUCTION OF KNOWLEDGE THAT YOU WANT YOUR STUDENTS TO ACQUIRE.



H
ow do you know right hand rule?



Why do you believe that magnetic interactions are different from electric int
eractions?



What is the difference between field vectors and field lines?


LENGTH TOTAL AND SUBUNITS



CLASS 1
.

Magnetic Fields


o

Class activities



Students work with ALG 17.1.1



Students work with ALG 17.1.2



Students work with ALG 17.1.3



Students work with

ALG 17.1.4

o

Homework



ALG 17.1.5



Problems from text book



CLASS 2.

Magnetic Fields

& Right Hand Rule # 1



o

Class activities



Students work with ALG 17.1.6



Students work with ALG 17.1.8



Students work with ALG 17.1.10



Students work with ALG 17.1.11



Discussion r
ight hand rule # 1



Watch this video:
Click here

(Physics Videos)

o

Homework



Problems from text book



CLASS 3.

Magnetic Force on a moving charge
& Right Hand Rule # 2

o

Class acti
vities



Students work with ALG 17.2.1



Students work with ALG 17.2.3



Discussion right hand rule # 2



Students work with ALG 17.2.4

o

Homework



Finish ALG 17.2.1



ALG 17.2.2



ALG 17.2.5



CLASS 4.

Magnetic force on a current
-
carrying wire

o

Class activities



Students w
ork with ALG 17.2.6.



Students work with ALG 17.2.8.



Students work with ALG 17.2.9.

o

Homework



ALG 17.2.7



Finish ALG 17.2.9



ALG 17.2.10



CLASS 5.

Mathematical representation for magnetic forces

o

Class activities



Students work with ALG 17.3.1



Students work with

ALG 17.3.2



Watch this video:
Click here

(Youtube Video)



Students work with ALG 17.4.1

o

Homework



Problems from text book



LABORATORY




Watch this video:
Click here

(Physics Video)



Watch this video:
Click here

(Physics Video)



CLASS 6.

Quantitative reasoning

o

Class activi
ties



Students work with ALG 17.4.2



Students work with ALG 17.4.5



Students work with ALG 17.4.6



Students work with ALG 17.4.7

o

Homework



ALG 17.4.3



ALG 17.4.4



CLASS 7.

Quantitative reasoning

o

Class activities



Students work with ALG 17.4.8



Students work with A
LG 17.4.9



Students work with ALG 17.4.10



Students work with ALG 17.4.11



Watch this video:
click here

(Youtube Video)



Watch this video:
clic
k here

(Youtube Video)

o

Homework



Problems from text book



CLASS 8.

Review

o

Review Session



CLASS 9.

Exam

o

Summative Assessment



STUDENT DIFFICULTIES



Students might think that magnetic poles are the same as electric charges.



Students might think that magne
tic forces are the same as electric forces.



Students might think that magnetic fields are “magnetic force fields”.



Students might

find difficult to figure out what the direction of the current is.



Students might

find difficult to figure out the direction o
f the magnetic field is.



Students might

find difficult to figure out hot to set up right hand rule number one



Students might choose the wrong system



Students might find difficult to translate Newton’s 2


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污w⁩ t漠浡gnet楳m.

RELEVANCE TO STUDENTS
’ LIVES


Magnets are used in every day’s life when:



Using a computer, a hard drive relies on magnets to store data, and some monitors use magnets to
create images on the screen.



Doorbells, uses an electromagnet to drive a noisemaker.



Magnets are also

vital components in CRT televisions, speakers, microphones, generators, transformers,
electric motors, burglar alarms, cassette tapes, compasses and car speedometers.



Magnets have numerous amazing properties. They can induce current in wire and supply t
orque for
electric motors.



A strong enough magnetic field can levitate small objects or even small animals.



Maglev trains use magnetic propulsion to travel at high speeds.



Magnetic fluids help fill rocket engines with fuel.



The Earth's magnetic fiel
d, known as the
magnetosphere
, protects it from the
solar wind
.



Magnetic Resonance Imaging (MRI) machines use magnetic fields to allow doctors to examine patients'
internal organs. Doctors also use pulsed electromagnetic fields to treat broken bones that

have not
healed correctly. This method, can mend bones that have not responded to other treatment. Similar
pulses of electromagnetic energy may help prevent bone and muscle loss in astronauts who are in zero
-
gravity environments for extended periods.



TEXTS AND MATERIALS PLANNED TO USE IN THE UNIT




Magnetic levitation transport
, or
maglev
1
, is a form of transportation that suspends guides and propels vehicles via
electromagnetic force. This method can be faster than wheeled mass transit systems, pote
ntially reaching velocities
comparable to turboprop and jet aircraft (500 to 580

km/h).


The world's first commercial application of a high
-
speed maglev line is the IOS (initial operating segment) demonstration
line in Shanghai, China that transports peopl
e 30 km (18.6 miles) to the airport in just 7 minutes 20 seconds (top speed
of 431

km/h or 268

mph, average speed 250

km/h or 150

mph). Other maglev projects worldwide are being studied for
feasibility. However, scientific, economic and political barriers
and limitations have hindered the widespread adoption of
the technology.


Maglev technology has minimal overlap with wheeled train technology and is not compatible with conventional railroad
tracks. Because they cannot share existing infrastructure, maglev
s must be designed as complete transportation
systems. The term "maglev" refers not only to the vehicles, but to the railway system as well, specifically designed for
magnetic levitation and propulsion.


Technology

There are two primary types of maglev tec
hnology:



Electromagnetic suspension (EMS) uses the attractive magnetic force of a magnet beneath a rail to lift the train
up.



Electrodynamic

suspension (EDS) uses a repulsive force between two magnetic fields to push the train away
from the rail.




1

http://en.wikipedia.org/wiki/Maglev_train


Electrom
agnetic suspension

In current EMS systems, the train levitates above a steel rail while
electromagnets
, attached to the train, are oriented
toward the rail from below. The
electromagnets

use feedback control to maintain a train at a constant distance from
a
track.


Electrodynamic suspension



In Electrodynamic suspension (EDS), both the rail and the train exert a
magnetic field, and the train is levitated by the repulsive force between these
magnetic fields. The magnetic field in the train is produced by e
ither
superconducting electromagnets (as in
JR
-
Maglev
) or by an array of
permanent magnets (as in
Inductrack
). The repulsive force in the track is
created by an
induced magnetic field

in wires or other conducting strips in
the track.


At slow speeds, the c
urrent induced in these coils and the resultant magnetic flux is not large enough to support the
weight of the train. For this reason the train must have wheels or some other form of landing gear to support the train
until it reaches a speed that can susta
in levitation.


Propulsion coils on the guideway are used to exert a force on the magnets in the train and make the train move
forwards. The propulsion coils that exert a force on the train are effectively a
linear motor
: An alternating current
flowing thr
ough the coils generates a continuously varying magnetic field that moves forward along the track. The
magnets on the train line up with this field, and the train moves.


Pros and cons of different technologies

Each implementation of the magnetic levitatio
n principle for train
-
type travel involves advantages and disadvantages.
Time will tell as to which principle, and whose implementation, wins out commercially.


TECHNOLOGY

PROS

CONS

EMS

(Electromagnetic)

Magnetic fields inside and outside the
vehicle are
insignificant; proven,
commercially available technology that
can attain very high speeds (500 km/h);
no wheels or secondary propulsion
system needed

The separation between the vehicle and
the guideway must be constantly
monitored and corrected by computer

systems to avoid collision due to the
unstable nature of electromagnetic
attraction.

Superconducting EDS

(Electrodynamic)

Powerful onboard superconducting
magnets and large margin between rail
and train enable highest recorded train
speeds (581 km/h) and

heavy load
capacity; has recently demonstrated (Dec
2005) successful operations using high
temperature superconductors (HTS) in its
onboard magnets, cooled with
inexpensive liquid nitrogen

Strong magnetic fields onboard the train
make the train inaccessib
le to passengers
with pacemakers or magnetic data
storage media such as hard drives and
credit cards, necessitating the use of
magnetic shielding; vehicle must be
wheeled for travel at low speeds; system
per mile cost still considered prohibitive;
the syst
em is not yet out of prototype
phase.

Inductrack System

(Permanent
Magnet EDS)

Failsafe Suspension
-

no power required
to activate magnets; Magnetic field is
localized below the car, can generate
enough force at low speeds (around 5
km/h) to levitate magl
ev train; in case of
power failure cars slow down on their
own in a safe, steady and predictable
manner before coming to a stop; Halbach
arrays of permanent magnets may prove
more cost
-
effective than electromagnets

Requires either wheels or track segments
that move for when the vehicle is
stopped. New technology that is still
under development (as of 2006) and has
as yet no commercial version or full scale
system prototype.


Neither Inductrack nor the Superconducting EDS are able to levitate vehicles at a
standstill, although Inductrack
provides levitation down to a much lower speed. Wheels are required for both systems. EMS systems are
wheel
-
less
.

The German Transrapid, Japanese HSST (Linimo), and Korean Rotem EMS maglevs levitate at a standstill, with
ele
ctricity extracted from guideway using power rails for the latter two, and wirelessly for Transrapid. If guideway power
is lost on the move, the Transrapid is still able to generate levitation down to 10 km/h speed, using the power from
onboard batteries.
This is not the case with the HSST and Rotem systems.


PROPULSION

An EMS system can provide both
levitation

and
propulsion

using an onboard linear motor. EDS systems can only levitate
the train using the magnets onboard, not propel it forward. As such, veh
icles need some other technology for
propulsion
. A linear motor (propulsion coils) mounted in the track is one solution. Over long distances where the cost of
propulsion coils could be prohibitive, a
propeller

or
jet engine

could be used.


STABILITY

Static

magnetic bearings using only electromagnets and permagnets are unstable, as explained by
Earnshaw's theorem
.
EMS systems rely on active electronic
stabilization
. Such systems constantly measure the bearing distance and adjust
the electromagnet current acc
ordingly. As all EDS systems are moving systems (i.e. no EDS system can levitate the train
unless it is in motion), Earnshaw's theorem does not apply to them.


PROS AND CONS OF MAGLEV VS. CONVENTIONAL TRAINS

Due to the lack of physical contact between the
track and the vehicle, there is no rolling
friction
, leaving only air
resistance (although maglev trains also experience electromagnetic drag, this is relatively small at high speeds).

Maglevs can handle high volumes of passengers per hour (comparable to
airports or eight
-
lane highways) and do it
without introducing
air pollution

along the
right of way
. Of course, the electricity has to be generated somewhere, so
the overall environmental impact of a maglev system is dependent on the
nature of the grid pow
er source
.

The weight of the large
electromagnets

in EMS and EDS designs are a major design issue. A very strong magnetic field
is required to levitate a massive
train
. For this reason one research path is using superconductors to improve the
efficiency of

the electromagnets.


Due to its high speed and shape, the noise generated by a maglev train is similar to a jet aircraft, and is considerably
more disturbing than standard steel on steel intercity train noise. A study found the difference between disturba
nce
levels of maglev and traditional trains to be 5dB (about 78% noisier)
.



ECONOMICS

The Shanghai maglev cost 9.93 billion yuan (US$1.2 billion) to build. This total includes infrastructure capital costs such
as manufacturing and construction facilities,

and operational training. At 50 yuan per passenge
r

and the current 7,000
passengers per day, income from the system is incapable of recouping the capital costs (including interest on financing)
over the expected lifetime of the system, even ignoring opera
ting costs.


China aims to limit the cost of future construction extending the maglev line to approximately 200 million yuan (US$24.6
million) per kilometer
.

These costs compare competitively with airport construction (e.g.,
Hong Kong Airport

cost US$20
bi
llion to build in 1998) and eight
-
lane
Interstate highway

systems that cost around US$50 million per mile in the US.

While high
-
speed maglevs are expensive to build, they are less expensive to operate and maintain than traditional high
-
speed trains, planes

or intercity buses. Data from the Shanghai maglev project indicates that operation and maintenance
costs are covered by the current relatively low volume of 7,000 passengers per day. Passenger volumes on the Pudong
International Airport line are expected
to rise dramatically once the line is extended from Longyang Road metro station
all the way to Shanghai's downtown train depot.


The proposed
Chūō Shinkansen

line is estimated to cost approximately US$
82 billion

to build.

The only low
-
speed maglev (100 km/
h) currently operational, the Japanese
Linimo

HSST, cost approximately US$100
million/km to build. Besides offering improved O&M costs over other transit systems, these low
-
speed maglevs provide
ultra
-
high levels of operational reliability and introduce li
ttle noise and zero air pollution into
dense

urban settings.

As maglev systems are deployed around the world, experts expect construction costs to drop as new construction
methods are perfected
.







LABORATORY

1.

TESTING EXPERIMENT: FORCE ON A MAGNET DUE
TO A CURRENT CARRYING WIRE (RIGHT HAND RULE #1)


Think of how you can use this equipment to test the right hand rule for the direction of the force exerted by a magnetic fiel
d on a
current carrying wire. Also, think of what physical quantities you could de
termine using the scale.


RUBRICS:

A3, A5, C1, C2, C3, C4


Available

equipment
:
A horseshoe magnet whose poles are known (Red: North, White: South), a scale, a wire through which a
current can flow, a voltage source, and connecting wires.


Warning: Do no
t leave the voltage source on after you finish the measurements.


a)

First, recall the right hand rule for the magnetic force. Write what quantities it relates and express it with a picture or u
sing
words. Consider the available equipment and how you could u
se it to achieve the goal of the experiment. Brainstorm and write
down your ideas including what you could measure and sketches of possible experimental setups).


b)

Describe your procedure. The description should contain a labeled sketch of your experimenta
l set
-
up, an outline of what you
plan to do, what you will measure, how you will measure it. Explain how you will use the reading of the scale to determine th
e
force exerted by the wire on the magnet, and the force exerted by the magnet on the wire. To hel
p, use free
-
body diagram(s)
and Newton’s second and third laws.


c)

Make a qualitative prediction for the reading of the scale (more than some value, less than some value) for your particular
arrangement. Show the reasoning used to make the prediction with f
ree
-
body diagrams. Call your TA over once you have done
this but before you turn on the current. Then perform the experiment and record the outcome.


d)

Did the outcome match your prediction? If not, list possible reasons.


e)

Based on your prediction and the
experimental outcome, make a judgment about the right
-
hand rule.


2.

TESTING EXPERIMENT: DOES A COIL BEHAVE LIKE A MAGNET?


Your friend Jim has an idea that a coil of wire with current flowing in it behaves like a bar magnet whose poles can be deter
mined usi
ng
right hand rule #2. Design an experiment to test his idea.


RUBRICS:

A7


AVAILABLE

EQUIPMENT:

A bar magnet (poles known), a long wire that you can use to make a coil with several turns, alligator clips,
a swivel, a voltage source.


a)

First recall what r
ight hand rule #2 says. Decide how you can apply it to determine the shape of the magnetic field of a current
carrying coil.


b)

Design an experiment to test Jim’ idea. Describe your procedure and draw a sketch of your experimental setup.


c)

Using Jim’ idea,
make a prediction of the outcome of the experiment. Explain the reasoning used to make the prediction in
detail. What assumption do you need to make the prediction?


d)

Use the wire to make a coil with several turns. Conduct the experiment and record the out
come.


e)

Did the outcome match the prediction?


f)

What is your judgment about Jim’ idea?


3.

WHY DID WE DO THIS LAB?




What was the purpose of using free
-
body diagrams in this lab? Describe the instances when the diagrams helped you make
decisions related to th
e collection of your data and the analysis.




Why was it important to consider the assumption you made in experiment III?



RUBRIC A


Ability to represent information in multiple ways



Scientific Ability

Missing

Inadequate

Needs some
improvement

Adequate

A3

Is able to evaluate the
consistency of different
representations and modify
them when necessary

No representation is made
to evaluate the consistency.

At least one representation
is made but there are major
discrepancies between the
constructed represe
ntation
and the given one.

Representations created
agree with each other but
may have slight
discrepancies with the given
representation. Can be seen
that modifications were
made to a representation.

All representations, both
created and given, are in
agre
ement with each other.

Representations students can make



Scientific Ability

Missing

Inadequate

Needs some
improvement

Adequate

A5

Free
-
Body Diagram

No representation is
constructed.

FBD is constructed but
contains major errors such
as incorrect mislab
eled or
not labeled force vectors,
length of vectors, wrong
direction, extra incorrect
vectors are added, or
vectors are missing.

FBD contains no errors in
vectors but lacks a key
feature such as labels of
forces with two subscripts
or vectors are not draw
n
from single point or axes
are missing.

The diagram contains no
errors and each force is
labeled so that it is clearly
understood what each force
represents.

A7

Picture

No representation is
constructed.

Picture is drawn but it is
incomplete with no physi
cal
quantities labeled, or
important information is
missing, or it contains a
wrong information, or
coordinate axes are
missing.

Picture has no incorrect
information but has either
no or very few labels of
given quantities. Majority of
key items are drawn
in the
picture.

Picture contains all key
items with the majority of
labels present.


RUBRIC C


Ability to design and conduct a testing experiment (testing an idea/hypothesis/explanation or mathematical relation)



Scientific Ability

Missing

Inadequate

Ne
eds some
improvement

Adequate

C1

Is able to identify the
hypothesis to be tested

No mention is made of
a hypothesis.

An attempt is made to
identify the hypothesis
to be tested but is
described in a confusing
manner.

The hypothesis to be
tested is describe
d but
there are minor
omissions or vague
details.

The hypothesis is clearly
stated.

C2

Is able to design a
reliable experiment that
tests the hypothesis

The experiment does
not test the hypothesis.

The experiment tests the
hypothesis, but due to
the natur
e of the design
it is likely the data will
lead to an incorrect
judgment.

The experiment tests the
hypothesis, but due to
the nature of the design
there is a moderate
chance the data will lead
to an inconclusive
judgment.

The experiment tests the
hypothesi
s and has a
high likelihood of
producing data that will
lead to a conclusive
judgment.

C3

Is able to distinguish
between a hypothesis
and a prediction

No prediction is made.
The experiment is not
treated as a testing
experiment.

A prediction is made but
i
t is identical to the
hypothesis.

A prediction is made and
is distinct from the
hypothesis but does not
describe the outcome of
the designed
experiment.

A prediction is made, is
distinct from the
hypothesis, and
describes the outcome
of the designed
experi
ment

C4

Is able to make a
reasonable prediction
based on a hypothesis

No attempt to make a
prediction is made.

A prediction is made that
is distinct from the
hypothesis but is not
based on it.

A prediction is made that
follows from the
hypothesis but does

not
incorporate assumptions

A prediction is made that
follows from the
hypothesis and
incorporates
assumptions.













FINAL SUMMATIVE ASSESSMENT


1.

Two parallel wires carry electric current in the same direction.
D
oes the
m
o
vi
n
g charge in one wire

cause a
magneti
c force to be exerted on the mov
ing charge in the other wire: If so, in what direction is the force relative
to the wires? Explain. Repeat for currents moving in opposite directions.



2.

Which of the following pictures best represents the ma
gnetic field lines created by a

wire with a current flowing in
it? The current is flowing into the page.


A

B

C

D

E





None of these


So
lution


Use right hand rule # 2


Answer is A.


3.

A

positively charged particle is at rest in a plane above and between two bars magnets, as shown in the figure.
Which choice below best represents the resulting magnetic force exerted by the magnets on the ch
arged particle?



A

B

C

D

E







Zero



Solution




Answer is D.


4.

An electron moves in a circle perpendicular to a 2.2x10
-
2

T magnetic field. If the electron’s speed is 1.5x10
7

m/s,
what is the r
adius of the circle?


A

B

C

D

E


2.2x10
-
3

m


3.9x10
-
3

m


1.5x10
-
2

m



1.5x10
-
3

m



3.9x10
-
4

m



Solution






Answer is B.


5.

You have a 2 m long copper wire that has a mass of 0.02 kg. It is connected
to two posts as shown. You want to
suspend it above the Earth so that it is stationary without any assistance from the posts. (I.e., the posts exert no
upward force on the wire.) If the Earth’s magnetic field is
3報M
J
5


at th楳i灯楮tI an搠灯楮t猠h潲楺潮ta
汬l int漠the
灡来Ⱐa猠獨潷n 楮 the f楧畲eⰠwhat cu牲rnt ⡭a杮楴g摥 an搠摩牥ct楯i⤠nee摳dt漠f汯l th牯r杨gthe w楲i 獯sthat the
w楲i⁩猠獵灰潲te搠dy⁴hea杮整楣⁦楥汤⁡汯ne?


A
) 3.33x10
3
A to the right


B) 3.33
x10
3
A to the right


C
)
6.67
x10
3
A to the left


D
) 3.33x10
2
A to the left


E
) 6.67x10
3
A to the left



Solution





Therefore




Current to the right (Right hand rule # 1)

Answer is A.


6.

An electron s
tarts out moving horizontally as shown. It then curves upwards, moving along the path shown in the
diagram because a magnetic field exerts a force on the electron. In what direction does the magnetic field point?



A
) Toward the bottom of the page.


B
) Tow
ard the top of the page.


C
) Into the page.


D
) Out of the page.


E
) In the direction of the curved path.


Solution


Answer is D.


STUDENT MODIFICATIONS



ENGLISH LEARNING STUDENTS (ELS)

o

Provide a list that would include new
words with definitions that students might not know from ELS
classes.

o

Suggested list:



Magnet

o

Bring a magnet and show its properties to the whole class.


o

Ask students who English is their first language and go over each definition asking them to explain the
m
with their own words.


o

Have materials ready for class and make sure ELS students know what they are, and know the correct
spelling and pronunciation.




VISUALLY IMPAIRED STUDENTS (VIS)

o

Make sure that v
isual material needs to be accompanied by a verbal des
cription.


o

Handouts should be available in large print, audiotape, computer disk, and/or Braille formats.


o

Large Print People who have some functional vision may be able to s
ee print if it is large enough.


o

Have meter sticks/ruler with big numbers.


o

Ask
your students for what is happening and where is happening to make sure that VIS will be aware of
what is happening.


o

By verbally spelling out a new or technical word, you will be helping the student with a vision
impairment, as well as for other students.



o

Describe, in detail, visual occurrences, visual media, and directions including all pertinent aspects that
involve sight.


o

Describe, in detail, all pertinent visual occurrences or chalkboard writing.


o

Whenever possible, use actual objects for three di
mensional representations.




EQUIPMENT AND RESOURCES FOR STUDENTS




http://paer.rutgers.edu/pt3/




http://en.wikipedia.org/wiki/Maglev_train




EQUIPMENT


o

B
ar magnet
s

(poles known)

o

H
orseshoe magnet whose poles are known

o

S
cale
s

o

W
ire
s

through which a current

can flow

o

Connecting wires

o

L
ong wire that you can use to make a coil with several turns

o

A
lligator clips

o

Sw
ivel
s

o

V
oltage source.

o

Compasses



REFERENCES



Instructor Edition for Active Learning Guide

by Alan Van Heuvelen, Eugenia Etkina | © 2006 |
Harper
Co
llins Publishers

| ISBN:
0
-
673
-
39
556
-
1

|



Physics “A General Introduction”
批b䅬An san eeuve汥n | ꤠ
1V8S

| Pea牳潮
-

䅤摩獯n 坥獬sy | 䥓䉎B
0805PV07V0⁼



Fi ve easy l essons “
獴牡t e杩g猠s潲⁳ cces獦u氠l hy獩c猠seach楮g


by⁒an摡汬⁄.⁋湩杨琠

©′004
|⁁ 摩獯n
坥獬sy
|⁉卂 :‰
-
805P
-
8702
-
1⁼



University Physics (
Sears and Zemansky’s
)
by Hugh D. Young and Roger A. Freedman
| © 2000 | Addison
Wesley | ISBN: 0
-
201
-
60322
-
5 |



Physics
by Paul Zitzewitz, Mark Davids, Robert Neff, Kelly Wedding
|
© 1995
| Mc Graw Hill | ISBN: 0
-
02
-
826722
-
2 |