Electric Current from Magnetism
Electromagnetic Induction
Electromagnetic Induction
• An electric current can
be produced in a circuit
by a changing magnetic
field
• This is referred to as
Faraday’s Law
Electromagnetic Induction
• As the loop moves in
and out of a magnetic
field, a current is
produced (or induced)
in the conductor
• A current can also be
produced by rotating
the circuit or changing
the magnetic field
Electromagnetic Induction
• A current is only
produced when the
conductor moves
perpendicular to the
magnetic field
• This is the only way that
the individual charges
experience a force from
the magnetic field and
move
Alternating Current
• As the loop of wire
spins within the
magnetic field between
the two magnets,
current is produced
when the wire moves
perpendicular to the
field
– “Flat” in the figure
Alternating Current
• When the loop moves
parallel to the field, no
current is produced
– When the loop is
“straight up and down”
Alternating Current
• In order for the loop to
complete a full rotation,
it becomes “flat” again,
but this time it is
moving the other
direction
– Current is produced, but
it moves in the opposite
direction
Alternating Current
• A current that changes
directions at regular
intervals
AC Generator
• Mechanical Energy is
used to turn the coil of
wire in a magnetic field
• As the coil (which
actually consists of
many coils) is turned,
alternating current is
produced
Electromagnetic Energy
• James Clerk Maxwell
develops equations in
mid-1860’s to describe
the nature of
electromagnetic waves
Electromagnetic Energy
• Because the movement
of charge produces a
magnetic field and a
magnetic field can
produce a current,
these two acting
together can carry
energy without using
matter
Electromagnetic Energy
• These electromagnetic
waves carry visible light,
radio signals, and x-rays
with different amount
of energy