IB PHYSICS-Year1 ESSENTIAL UNIT 10 (EU10)

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16 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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IB PHYSICS
-
Year1

(SECONDARY)



ESSENTIAL UNIT

10

(EU
10
)


ELECTR
I
C CURRENTS AND ELECTROMAGNETIC INDUCTION

(2011
)


Unit Statement
:


In this unit students are introduced to the principles that govern production, transmission, measuring of
and uses of electric current.

Understanding and harnessing of
the power of flowing electric charge changed t
he quality of hu
man
life arguably more than the harnessing of any
other natural phenomena
.
Strangely, no one is in awe
anymore when

witnessing all of the
amazing things that happen when one turns on a switch
.


SL students should not be required to complete TSWs 16
-
34. T
hese are required for HL students only.


Essential Outcomes
:
(Must be Assessed)


1. TSW
Define electric current

2. TSW
Define resistance

3
. TSW
Apply the equation for resistance in the form





, where ρ is the resistivity of the material
of the resistor.

4
.
TSW

State Ohm’s law

5
.
TSW

Compare ohmic and non
-
ohmic behavior

6
. TSW
Derive and apply expressions for electric power dissipation in resistors

7
. TSW

Solve problems involving potential
difference, current and resistance


8
. TSW
Define electromotive force (emf)

9
.

TSW
Describe the concept of internal resistance

10
. TSW

Apply the equations for resistors connected in series and parallel

11.

TSW

Draw circuit diagrams

12. TSW
Describe the us
e of ideal ammeters and
ideal
voltmeters

13. TSW
Describe a potential divider

14. TSW
Explain the use of sensors in potential divider circuits


15. TSW
Solve problems involving electric circuits



HL only


16. TSW

Describe the inducing of an emf by
relative motion between a conductor and a magnetic
field.

17. TSW

Derive the formula for the emf induced in a straight conductor moving in a magnetic field.

18. TSW

Define magnetic flux and magnetic flux linkage.

19. TSW

Describe the production of an induc
ed emf by a time
-
changing magnetic flux.

20. TSW

State Faraday’s law and Lenz’s law



21. TSW
Solve electromagnetic induction problems.

22. TSW

Describe the emf induced in a coil rotating within a uniform magnetic

field.

23. TSW

Exp
lain the operation of a basic
alternating current (ac) generator.

24. TSW

Describe the effect on the induced emf of changing the generator frequency.

25. TSW

Discuss what is meant by the root
mean squared (rms) value of an
alternating current or
voltage.

26. TSW
State the relation between peak and rms values for sinusoidal currents and voltages.

27. TSW
Solve problems using peak and rms values.

28. TSW
Solve ac circuit problems for ohmic resistors.

29. TSW
Describe the operation of an ideal transformer and

solve problems on the operation of

ideal transformers.

30. TSW
Outline the reasons for power losses in transmission lines and real transformers.

31. TSW
Explain the use of high
-
voltage step

up and step
-
down transformers
in the
transmission of
electrical
power.

32. TSW

Solve problems on the operation of real transformers and power transmission.

33. TSW
Suggest how extra
-
low
-
frequency electromagnetic fields, such as those created by electrical
appliances and power lines, induce currents within a human body.

34. TSW

Discuss some of the possible risks involved in living and working near high
-
voltage power
lines.


Suggested Materials
:

Textbook, Syllabus, Data Booklet, PSOW form, Physics Core Investigations

IB Question Bank CD; topic
Electricity &

Magnetism

LogerPro (Vernier software) and probes

Graphical Analysis software


T
echnology

Resources:

PhET computer simulations:

Ohm’s law, Battery voltage, Battery resistor circuit, Resistance in a wire,
Faraday’s electromagnetic lab, Circuit construction, etc.

http://phet.colorado.edu/en/simulations/category/new

Chris Hamper’s web page:
http://www.rcnuwc.org/ibphysics/

Online Curriculum Center:
http://occ.ibo.org/ibis/occ/guest/home.cfm

Destiny and Web Path Express (available through your library)


Suggested internal assessment for the unit:

4 hours of IA or more

Physics
Core
Investigation
s;

Investigation 14
-

Ohm

s Law

Investigation 15
-

Internal Resistance Of A Dry Cell

Investigation 16
-

Heating Eff
ect Of A Current

Investigation 18
-

Voltage Divider Circuits


The suggested simulations are suitable for several interesting investigati
ons
.

What is the relationship between the number of loops and voltage generated?

What is the relationship between el. current and the strength of the generated electromagnet?



Suggested Instructional Strategies:

The students should be given examples of questions from previous IB exams.

Teachers should use questions and problems from the IB question bank.


Give students time to play with dry cells, resistors, light bulbs, magnets, volt and ampmeters….

Take your c
lass on a field trip to a local power plant.

Discuss “the war of the currents” between T.A. Edison (DC) and Nicola Tesla (AC). What would the
world be like if DC had wan “the war?”

Challenge your students (and yourself) to go through one day without using
any electricity at all.



Suggested a
ssessment

of mastery and beyond mastery of the unit:

It is strongly recommended

that questions from past IB exams and from the IB question bank are used
for asses
sing mastery and beyond mastery
.

Each TSW should be asses
sed

with at least one question/problem. Some questions (for example
extended
-
response questions
) can assess the mastery of more than one TSW.


B

A

To earn a B student

will correctly answer
most

questions that asses Lower Order
T
hinking Skills (LOTS) and
some

questions
that assess Higher Order Thinking Skills
(HOTS).

SOME means at least a half

MOST means at least 70
%


To earn an A student

will correctly answer
most questions that asses Lower Order
Th
inking Skills (LOTS) and most
questions
that assess Hig
her Order Thinking Skills
(HOTS).


MOST mean at least 70%






For more detailed information on assessment of mastery and beyond mastery see the
Suggested
Resources folder
.