C CURRENTS AND ELECTROMAGNETIC INDUCTION
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
life arguably more than the harnessing of any
other natural phenomena
Strangely, no one is in awe
witnessing all of the
amazing things that happen when one turns on a switch
SL students should not be required to complete TSWs 16
hese are required for HL students only.
(Must be Assessed)
Define electric current
Apply the equation for resistance in the form
, where ρ is the resistivity of the material
of the resistor.
State Ohm’s law
Compare ohmic and non
Derive and apply expressions for electric power dissipation in resistors
Solve problems involving potential
difference, current and resistance
Define electromotive force (emf)
Describe the concept of internal resistance
Apply the equations for resistors connected in series and parallel
Draw circuit diagrams
Describe the us
e of ideal ammeters and
Describe a potential divider
Explain the use of sensors in potential divider circuits
Solve problems involving electric circuits
Describe the inducing of an emf by
relative motion between a conductor and a magnetic
Derive the formula for the emf induced in a straight conductor moving in a magnetic field.
Define magnetic flux and magnetic flux linkage.
Describe the production of an induc
ed emf by a time
changing magnetic flux.
State Faraday’s law and Lenz’s law
Solve electromagnetic induction problems.
Describe the emf induced in a coil rotating within a uniform magnetic
lain the operation of a basic
alternating current (ac) generator.
Describe the effect on the induced emf of changing the generator frequency.
Discuss what is meant by the root
mean squared (rms) value of an
alternating current or
State the relation between peak and rms values for sinusoidal currents and voltages.
Solve problems using peak and rms values.
Solve ac circuit problems for ohmic resistors.
Describe the operation of an ideal transformer and
solve problems on the operation of
Outline the reasons for power losses in transmission lines and real transformers.
Explain the use of high
up and step
Solve problems on the operation of real transformers and power transmission.
Suggest how extra
frequency electromagnetic fields, such as those created by electrical
appliances and power lines, induce currents within a human body.
Discuss some of the possible risks involved in living and working near high
Textbook, Syllabus, Data Booklet, PSOW form, Physics Core Investigations
IB Question Bank CD; topic
LogerPro (Vernier software) and probes
Graphical Analysis software
PhET computer simulations:
Ohm’s law, Battery voltage, Battery resistor circuit, Resistance in a wire,
Faraday’s electromagnetic lab, Circuit construction, etc.
Chris Hamper’s web page:
Online Curriculum Center:
Destiny and Web Path Express (available through your library)
Suggested internal assessment for the unit:
4 hours of IA or more
Internal Resistance Of A Dry Cell
ect Of A Current
Voltage Divider Circuits
The suggested simulations are suitable for several interesting investigati
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.
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
sing mastery and beyond mastery
Each TSW should be asses
with at least one question/problem. Some questions (for example
) can assess the mastery of more than one TSW.
To earn a B student
will correctly answer
questions that asses Lower Order
hinking Skills (LOTS) and
that assess Higher Order Thinking Skills
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
inking Skills (LOTS) and most
that assess Hig
her Order Thinking Skills
MOST mean at least 70%
For more detailed information on assessment of mastery and beyond mastery see the