P4

magnetism (4)

• Non-contact force

• 3D fields

• Opposites attract, like repel

• Flow from north to south pole

magnetic materials

iron, cobalt and nicker are the only pure metals capable of becoming permanent magnets

magnetic field behaviours(3)

1. Direction from north to south

2. Indicates a stronger field where they are closer to the magnet

3. Shows the shape of the field around a magnet

induced magnetism

when a magnetic material becomes a magnet so long as it is placed in a magnetic field

electromagnet

a temporary magnet (only) created by passing an electric current through a coil of wire, usually wrapped around a soft iron core,

electromagnet diagram

direction of current flows with the arrows

testing methods

• compass to show the wire has become a magnet

• iron fillings on card to show shape of the wire’s magnetic field

right-hand rule

• finger represents current

• clockwise = finger down, anticlockwise= finger up

solenoid

coils of wire tightly packed together

strengthening a solenoid

• Iron core (magnetic) to strengthen the magnetic field via induced magnetism

• more coils = more individual magnetic fields

• more current = stronger field

magnetic field of a solenoid

right grip rule

finds North Pole of a solenoid

• fingers around the coil as current direction

• the thumb = north