physics magnetism and electromagnetism gcse

soft magnetic field

temporary magnet e.g. iron

hard magnetic field

long term magnet e.g. steel

magnetic field lines rules (3)

never cross

stronger magnet = closer together

north to south

right hand grip rule

thumb = current

fingers = field

direction of fingers = direction of arrows on field lines

how to increase strength of magnetic field

increase current/voltage

increase no. of coils

what is an electromagnet

iron core + wire creating soft magnetic field

describe motor effect

current carrying wire has magnetic field around it

current carrying wire is put between 2 magnetic poles + 2 magnetic fields interact

creates a force which moves wire

in interaction, energy is transferred electrically + leaves as thermal energy store in wire

left hand wire

pointer finger = field North to south

middle = direction of current

thumb = direction of force

how does motor work

current flows through wire

magnetic field is created around wire

magnetic field interacts with permanent magnets

wire feels a force and moves

1 side moves up and other side moves down

split ring reverses current every half turn

explain how a loudspeaker works

current flows through wire

creates magnetic field around wire

magnetic field interacts with permanent magnets

speaker feels a force + moves

Alternating current causes the field to change and the force to reverse

Speaker vibrates