Download R Ch 37 Electric Induction pg 1

R Ch 37 Electromagnetic
Induction pg 1
Text Qs pg 592
RQ 2, 3, 7, 9-14, 16-18, 20, 21
R Ch 37.1 Electromagnetic
Induction pg 2
• In 1831 Faraday found you could produce
an electric current moving a magnet and
wire.
• Electromagnetic Induction – causing a
voltage by changing the magnetic field
around a coductor
R Ch 37.1 Electric Induction pg 3
• The voltage that can be induced depends on;
• 1) the speed of the motion (fast motion = big voltage)
• 2) the wire motion is at a right angle to the
magnetic field
• 3) more loops of wire crossing the magnetic
field = more voltage & more current
R Ch 37.2 Faraday’s Law pg 4
• Faraday’s Law – move a conductor through
a magnetic field and create a voltage &
current.
• move an insulator through a magnetic field
and create a voltage but no current
R Ch 37.3 Generators &
Alternating Current pg 5
• Generators – convert mechanical energy to
electric energy
• Motors – convert electric energy to
mechanical energy
• A generator spins a coil of wire inside a
magnet, and as it spins the N pole & S pole
pull the electrons back and forth causing
AC (alternating) current
R Ch 37.3 Generators &
Alternating Current pg 6
• Batteries have DC (direct) current
• In North America the voltage & current
change in strength 60 times a second and it
is called 60 cycle or 60 Hertz current
R Ch 37.4 Motor & Generator
Comparisons pg 7
• Motors spin around because a current in the
wire feels a force from a magnet
• Generators spin around because something,
wind, water or steam pushes the wire
around inside a magnet
R Ch 37.5 Transformers pg 8
• Transformers are squares of iron used to
increase or decrease the voltage and current
of AC circuits only.
• Step-up Transformer – increases v & c
• Step-down Transformer – decreases v & c
• Primary coil – wire into transformer
• Secondary coil – wire out of transformer
R Ch 37.6 Power Transmission
pg 9
• All electric energy sold today is AC because
it is easy to step up and step down
• Power ->Tall -> Backyard ->House
• Plant
tower
pole
• 6,000 v 100,000 v 6,000 v
120 v
R Ch 37.6 Power Transmission
pg 10
• Electromagnetic induction is all that current
electricity is and it turns out it is all that TV
& radio are, controlled electromagnetic
induction
R Ch 37.7 Induction of Electric
& Magnetic Fields pg 11
• Faraday said – an electric field is created
where a magnetic field changes with time
• Maxwell said – an magnetic field is created
where an electric field changes with time
• These two ideas created the technology that
we live with today
R Ch 37.8 Electromagnetic
Waves pg 12
• Electromagnetic waves move at the speed
of light 300,000 km/s or 186,000 miles/s
• Because a changing electric field is creates
a magnetic field & a changing magnetic
field is creates a electric field the two fields
regenerate each other.
R Ch 37.8 Electromagnetic
Waves pg 13
• Electromagnetic Waves have an magnetic
half and an electric half that;
• 1) move as a wave
• 2) are at 90 degrees to each other
• 3) they can move through a vacuum (space)