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.

Centre finger = Conventional Current

First finger = Field direction

Thumb = Motion

Building a loudspeaker

These also use the motor effect

Coil in here

magnet

HomeworkPages 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 coilbrushes

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.