Topic 4.1 - The simple phenomena of magnetism Flashcards
What is a magnetic field?
A region where magnetic objects experience a force.
Where is a magnetic field strongest?
At the poles of a magnet.
Magnetic field strength decreases as…
Distance from the magnet increases.
Where does attraction occur?
Between opposite (unlike) poles of two magnets.
Where does repulsion occur?
Between like poles of two magnets.
Describe the key features of field lines in a magnetic diagram
- They have arrows pointing from north to south.
- The lines never touch, cross or overlap.
How is the strength of a magnet displayed in a diagram?
By the spacing of the field lines (the closer together they are, the stronger the magnet).
What do the arrows on field lines represent?
The direction of the force that would be experienced by the north pole of a magnet placed in the field.
What is a permanent magnet?
An object which always has poles, and is therefore always magnetic.
What is an induced magnet?
A magnetic material which does not have fixed poles. They can be induced to become magnets (giving them poles) by placing them in a magnetic field, but they lose their magnetisation when the field is removed.
What is a magnetic material?
A material that is attracted to a magnet and can be magnetised.
Give examples of magnetic materials.
Iron, steel, cobalt, nickel etc.
Describe how materials are magnetised.
- Stroking them with a magnet
- Hammering them in a magnetic field
- Placing them in a coil with a direct current through it
Describe how materials are demagnetised
- Hammering
- Heating
- Placing in a coil with an AC wire
What is a magnetically hard material?
A material which can be permanently magnetised.
