Transcript Do now! - MrSimonPorter

Do now!
Can you read page 212 of
your text book?
Last lesson
• The motor effect and building a
loudspeaker
The Motor Effect
When a current is placed in a magnetic
field it will experience a force (provided the
current is not parallel to the field). This is
called the motor effect.
Can you
copy this
sentence
into your
books
please.
The Motor Effect
The direction of the force on a current in a
magnetic field is given by Flemming’s left
hand rule.
Thumb = Motion
First finger = Field direction
Centre finger = Conventional Current
Building a loudspeaker
These also use the motor effect
Coil in here
magnet
Homework
Pages 210 to 213. Answer the
questions on all pages. Finish for
homework due 15th October
Today’s lesson
• How the motor effect can build a motor
• Electromagnetic induction
Gather round!
D.C.Motor
Commutator ensures that every
half rotation the current
direction reverses in the coil
brushes
D.C.Motor
Electromagnetic induction
• Make a coil using wire. The coil should be
wide enough to easily move a magnet
inside
Electromagnetic induction
• Put your coil in this circuit. The multimeter
should be on the μA scale.
μA
Electromagnetic induction
• MOVE a magnet in and out of the coil.
Watch the meter!
μA
Electromagnetic induction
If a magnet is
moved inside a
coil an electric
current is
induced
(produced)
Electromagnetic induction
If a magnet is
moved inside a
coil an electric
current is
induced
(produced)
COPY this please!
Electromagnetic induction
A electric current is induced because the
magnetic field around the coil is changing.
Gather round
Again?
Generator/dynamo
A generator
works in this way
by rotating a coil
in a magnetic
field (or rotating a
magnet in a coil)
Motor = generator
If electric energy enters a motor it is
changed into kinetic energy, but if kinetic
energy is inputted (the motor is turned)
electric energy is produced!
Let’s try some questions!
Pages 214 and 215.