Summary AQA GCSE Physics Combined Science - Magnetism Notes

MAGNETISM
MAGNETS
 Matching poles repel each other
 Opposite poles attract each other
 Permanent magnet: a magnet that has a constant magnetic field, and can attract and repel
 Induced magnet: a magnet that has a temporary field, and can only attract
 Examples of magnetic materials: iron, steel, cobalt, nickel
 MAGNETIC FIELDS
o Field lines travel north to south
o The strongest magnetic field is located at the poles
o The strength of a magnetic field can be determined by how close the field lines are
 Closer together where the field is strongest
 EARTH’S CORE
o We know that the Earth’s core creates a large magnetic field around the earth as a
freely suspended magnetic compass will align itself with the Earth’s field lines and
point north




CURRENT
 A current produces a magnetic field around a wire
o The ‘right hand grip rule’ dictates the direction of this:
 Thumb = direction of current
 Other fingers = direction of the field
 STRENGTH OF A MAGNETIC FIELD
o The strength of a magnetic field can be changed by:
 A greater current which creates a stronger magnetic field
 A greater distance from the wire which creates a weaker field
 SOLENOID
o A solenoid is a coil of current-carrying wire that produces a magnetic field
o A solenoid having an iron core increases its strength as it makes it easier for the
magnetic field lines to pass through it than air
o How a solenoid affects a magnetic field:
 Enhances the field as coiling the wire causes the field to align and form a
giant single field, rather than lots of them that are all perpendicular to
the direction of the current
o Factors that affect the strength of a solenoid:
 Size of a current
 Length
 Cross-sectional area
 Number of coils
 Using a soft iron core

MOTOR EFFECT