Magnets produce a magnetic field and attract ferromagnetic objects
The force of attraction is greater at the poles than in the middle
Like poles repel and opposite poles attract
If free to rotate, the north(-seeking) pole rotates to face the north pole, and vice versa
Induced magnetism
Induced magnetism is when a unmagnetised but magnetic substance becomes magnetised near a magnet
Ferrous & non-ferrous metals describe metals & alloys that do & do not, respectively, contain iron in appreciable amounts
Methods of magnetising a ferromagnet: placing it in a magnetic field, enhanced by vibrating; stroking a magnet along it
Methods of demagnetising a ferromagnet: placing it in a reverse or alternating magnetic field; hammering or jarring
The field lines of a bar magnet can be displayed from the alignment of iron filings dispersed on a piece of paper below which is placed the magnet
Iron and steel can both be used as magnets: iron becomes magnetised faster when induced but loses it immediately upon removal; steel becomes magnetised slower but retains its magnetism
Electromagnets are made from iron and useful since the strength of the magnetic field can be changed rapidly by adjusting the amount of current in the winding
Permanent magnets are made from steel and more useful when there isn’t a source of electricity present to induce an electromagnet