Do now! Can you stick the sheet in your book please?

Do now!

Can you stick the sheet in your book please?

Last lesson

• Field around a wire

Moving charges (currents)

Moving charges (electric currents) also produce a magnetic field

http://www.sciencebuddies.org

Conventional current – electrons flow in the opposite direction

Magnetic field around a straight wire

Stronger field closer to wire

You can use the right hand screw rule to decide which direction the field goes

To make an electromagnet stronger?

To make an electromagnet strongerThe 3 C’s

• More Coils

• More Current

• Use an iron Core

Today’s lesson

• Field patterns around a wire, solenoid and coil.

• The motor effect

• Making a loudspeaker

Shape around a single coil of wire

Field around a coil

A side view

Field around a solenoid (coil)

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

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 (+ to -)

First finger = Field direction (N to S)

Thumb = Motion

Can you copy this please?

WITH DIAGRAM!

Sample question

In this example, which way will the wire be pushed? (red is north on the magnets)

Sample question

In this example, which way will the wire be pushed? (red is north on the magnets)

Current

Field

Building a loudspeaker

These also use the motor effect

Coil in here

magnet