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5
Electricity and Magnitism, 11
Electromagnitism Unit
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Section Number
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Topic
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Descriptor
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Topic 5:
Electricity and Magnetism (15h)
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5.1
Electrostatics (6h)
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Electric
charge
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5.1.1
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Describe the process of
ÒelectrificationÓ by friction.
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5.1.2
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State that there are two types
of electric charge.
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5.1.3
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State and apply the concept of
conservation of charge.
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5.1.4
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Describe and explain the
properties of conductors and insulators.
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Students should
explain the properties in terms of the freedom of
movement of
electrons.
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5.1.5
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Explain and describe the
process of electrostatic induction.
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5.1.6
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Describe the use of the gold
leaf electroscope.
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Electric force
and electric field
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5.1.7
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State Coulomb's
law.
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Students should be
aware of the law in the forms 202
14 rq q
F£k£`=and
F = . .
22
1rq kq
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5.1.8
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Apply Coulomb's
law.
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The use of vector
addition to determine the net force on a charge due
to
two or more other
charges is expected.
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5.1.9
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Define electric
field.
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Students should
understand the meaning of test charge.
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5.1.10
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Determine the electric field
due to one or more point charges.
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5.1.11
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Draw and explain electric
field patterns for different charge
configurations.
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Students should be
familiar with a point charge, a charged sphere,
two
point charges and
oppositely charged parallel plates. The latter
includes
edge effect.
Students should be aware of the term radial
field.
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Electric
potential energy and electric potential
difference
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5.1.12
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Define the electric potential
energy difference between two points in an
electric field.
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Calculations are to
be confined to uniform electric fields.
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5.1.13
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Determine the change in
potential energy or change in kinetic energy when
a charge moves between two points
at different potentials.
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5.1.14
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Define the
electronvolt.
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Students should be
able to relate the electronvolt to the joule.
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5.1.15
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Define electric potential
difference.
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5.1.16
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Solve problems involving
electric potential difference and electric potential
energy.
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5.2 Electric
Current and Electric Circuits (6h)
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Electric
current
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5.2.1
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Describe a simple model of
electrical conduction in a metal.
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Students should be
aware of the term drift velocity and of the
interactions of
conduction electrons with the lattice ions.
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5.2.2
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Define electric
current.
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Students should
recognize the ampere as a fundamental unit.
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5.2.3
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Define and apply the concept
of resistance.
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Students should be
aware that R = V/I is a general definition of
resistance. It
is not a statement of Ohm's law. Students should be familiar
with the term
resistor.
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5.2.4
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State Ohm's law.
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5.2.5
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Compare ohmic and non-ohmic
behaviour.
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For example,
students should be able to draw the I-V characteristics of
a filament
lamp.
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5.2.6
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Derive and apply expressions
for electrical power dissipation in resistors.
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Electric
circuits
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5.2.7
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Define electromotive
force.
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5.2.8
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Describe the concept of
internal resistance.
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5.2.9
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Derive and apply the equations
for equivalent resistances of resistors in
series and in
parallel.
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5.2.10
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Draw circuit
diagrams.
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Students should be
able to recognize and use the accepted circuit
symbols included
in the Physics Data Booklet.
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5.2.11
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Describe the use of ammeters
and voltmeters.
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Students should be
able to describe and draw the correct positioning of
ideal ammeters and
voltmeters in circuits. Students will not be required
to know about
shunts and multipliers.
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5.2.12
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Solve problems involving
series and parallel circuits.
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Students should
appreciate that many circuit problems can be solved
by regarding the
circuit as a potential divider. Students should be aware
that ammeters
and voltmeters have their own resistance.
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5.3 Magnetism
(3h)
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Magnets and
magnetic fields
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5.3.1
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Draw the pattern of magnetic
field lines of an isolated bar magnet.
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5.3.2
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Draw the magnetic field
pattern for the Earth.
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Students should
understand that the Earth's magnetic field is similar to
that of a bar
magnet with a south magnetic pole near the geographic north
pole, and that
an isolated suspended magnet will orientate itself along
the Earth's
magnetic field with its magnetic north pole directed towards
the Earth's
geographic north pole. They should recognize the compass as
one example of a
suspended bar magnet.
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5.3.3
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Draw and annotate magnetic
fields due to currents.
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These include fields
around a straight wire, a flat circular coil and a
solenoid. Students
should recognize that the magnetic field pattern of a
solenoid is similar to
that of a bar magnet.
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Magnetic
forces
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5.3.4
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Determine the direction of the
force on a current-carrying conductor in a
magnetic field.
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Different rules may
be used to determine the force direction. Knowledge
of any particular rule
is not required.
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5.3.5
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Determine the direction of the
force on a charge moving in a magnetic field.
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5.3.6
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Define the magnitude of the
magnetic field strength B.
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This can be defined
in terms of the force acting either on a
current-carrying conductor
or on a moving charge.
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5.3.7
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Solve problems involving the
magnetic forces on currents and moving charges.
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Students should be
able to calculate the force for situations where the
velocity is not
perpendicular to the magnetic field direction.
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5.3.8
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Draw the magnetic field
pattern due to two parallel current-carrying
wires.
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5.3.9
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Solve problems involving the
magnetic forces between two parallel currentcarrying
wires.
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5.3.10
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State and explain the
definition of the ampere.
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Students should be
able to explain how the force between two long
parallel currents is
the basis of the definition of the ampere.
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5.3.11
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Explain the operation of a
simple direct current (dc) motor.
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Students should
understand the components of dc motors, such as the
commutator and the
brushes.
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The magnetic
field due to currents
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5.3.12
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Solve problems involving the
magnetic field strength around a straight wire.
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5.3.13
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Solve problems involving the
magnetic field strength within a solenoid.
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Students should be
aware that B depends on the nature of the
solenoid core.
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Topic 11:
Electromagnetism (9h)
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11.1
Electrostatic Potential (3h)
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Electric
potential due to a point charge
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11.1.1
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Define electric
potential.
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Students should
understand the scalar nature of potential and that
the potential at
infinity is taken as zero.
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11.1.2
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Determine the electric
potential due to various charge configurations.
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This includes single
point charge, collections of point charges and the
potential outside a
charged sphere. Students will not be expected to
derive the equation
V = .rq0
4
£k£`
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11.1.3
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State and apply the formula
relating electric field strength to potential
gradient.
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It is sufficient
that students know that E =
-ÆV/Æx.
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11.1.4
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Describe the similarities and
differences between gravitational fields and
electrical fields.
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Equipotentials
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11.1.5
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Describe and sketch patterns
of equipotential surfaces.
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This should include
patterns due to isolated point charges, charged
conducting spheres, two
point charges and parallel conducting
plates.
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11.1.6
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Explain the relation of
equipotential surfaces to electric field lines.
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11.2
Electromagnetic Induction (4h)
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Induced
electromotive force (e.m.f.)
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11.2.1
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Describe the production of an
induced e.m.f. by relative motion between
a conductor and a magnetic field (motionally induced
e.m.f.).
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11.2.2
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Derive the formula for the
e.m.f. induced in a straight conductor moving
in a magnetic field.
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11.2.3
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Define magnetic flux
and flux linkage.
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11.2.4
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Describe the production of an
induced e.m.f. that is produced by a time-changing
magnetic flux.
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11.2.5
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State Faraday's
law.
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11.2.6
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Explain how a motionally
induced e.m.f. can be equated to a rate of
change of magnetic
flux.
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Students should be
able to show that the induced e.m.f. , Blv, is
equal to
t ÆÆ
£p
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11.2.7
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State Lenz's law.
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11.2.8
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Solve electromagnetic
induction problems.
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11.3
Alternating Current (2h)
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11.3.1
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Describe the e.m.f. induced in
a coil rotating within a uniform magnetic
field.
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Students should
understand, without deriving, that the induced e.m.f.
is sinusoidal if the
rotation is uniform.
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11.3.2
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Explain the operation of a
basic alternating current (ac) generator.
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11.3.3
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Define the concepts of root
mean square voltage and root mean square current.
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11.3.4
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Solve ac circuit problems for
ohmic resistors.
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11.3.5
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Describe the components and
characteristics of an ideal transformer and
explain its operation.
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A qualitative
explanation is sufficient.
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11.3.6
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Explain the use of high
voltage step-up and step-down transformers in
the transmission of electric
power.
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11.3.7
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Solve problems on the
operation of ideal transformers and power
transmission.
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