Magnetism Flashcards
What is in the space around a magnet
A magnetic field
Rules of field lines
They go from north to south
They never touch or cross other field lines
magnetic forces
Caused by the interaction of magnetic fields
What are the four magnetic materials
Iron
Steel
Nickel
Colbalt
What are the characteristics of magnetic soft materials
Easy to magnetise
Easily lose their magnetism
What are characteristics of magnetic hard materials
Hard to magnetise
Do not easily lose their magnetism
What are permenant magnets made out of
magnetic hard materials
What are electromagnets made of
magnetic soft materials
What is induced magnetism
When a magnetic material is placed in a magnetic field, the material becomes temporarily magnetised
It will gain North and south poles
When the field is removed is starts to lose its magnetism
Ways to create a magnet
A magnetic material can be magnetised by stroking it with one end of another magnet
Placing a magnetic material in a coil then passing a direct current through the coil will also magnetise it
Hitting the magnetic material with a hammer while in a magnetic field
Methods of demagnetisation
Hit the material with a hammer (when not in a magnetic field)
Heat the material until it begins to glow then let it cool
Place the material in a coil containing alternating current
How is an electromagnet created
When a current (d.c.) is passed through a long coil, the current creates a magnetic field around the coil similar to that of a bar magnet
Advantages of an electromagnet
Can be turned on and off
How is the strength of an electromagnet increased
Increasing the current in a coil
Adding more turns to the coil
