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Electromagnetic Induction
Electromagnetic Induction
 Motion of a magnet in a coil or loop creates (induces) ____________
 If coil is connected to complete circuit, _________ flows
 __________ motion is needed—it doesn’t matter which moves, the magnet or
the coil
 Amount of voltage depends on __________ and ________________ in coil
Faraday’s Law
 The induced voltage is proportional to the ______________ times the rate of
change of the _________________
 Magnetic field is changed by __________ or by changing the strength of the
field in an __________________
Generators
 Rotating a coil in a magnetic field will create __________________
 As coil rotates, amount of magnetic field ______________ by loop changes,
inducing a changing voltage
 Frequency of alternating current is the same as ____________ of rotation of
the coil
 Energy is converted from some ____________ form to ____________
Motors and Generators
 Both have same parts
 Motors convert ____________ energy to _____________ movement using
the magnetic force on a moving charge to move the coil
 Generators convert _____________ to ___________- by using the magnetic
force due to the coil movement to move the charges through the wire
Transformers
 Two coils of wire wound on the same iron core so that changes in the
magnetic field of the first coil (primary) induce ___________ across the
second coil (secondary)
 If ac flows through primary, ac is ___________ in secondary
 Voltage in secondary depends on ______________ between primary and
secondary
 If secondary has more turns, than transformer is called __________ and
voltage is ______________
 If secondary has fewer turns, then is called __________ and voltage is
____________
 Power is not increased so if voltage is stepped up, current is ___________
Transformer Equations
Primary turns
=
Primary voltage
Secondary turns
Secondary voltage
(Voltage x current)p = (voltage x current)s
Power Transmission
 Almost all electrical energy is sold as _____ because it is easy to change
_________________ using __________________
 High voltage and fairly low _________________are used to transmit power
over long distances
 This reduces losses due to _________________ in the wires
 Voltage is stepped down to _________________ for homes
Electric and Magnetic Fields
 Faraday’s law holds even if no _________________ is present
 A changing _________________ field induces an _________________ field
 Maxwell extended Faraday’s idea to say a changing _________________
field induces a _________________ field
 Electrical and magnetic fields are _________________ to each other
 Magnitude of _________________ field is proportional to
_________________ of the other field
 Explained operation of __________________________________
 __________________________________is the only speed where induction
will continue without energy gain or loss