play with your magnets!. all magnets have two poles north seeking pole south seeking pole
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Play with your magnets!
ALL magnets have two poles
NORTH seeking pole
SOUTH seeking pole
Breaking a magnet produces two magnets!
N S
N S
NN SS
Opposites attract!
Opposite poles attract and like poles repel
Magnetic materials
Magnetic materials
Iron (steel), Cobalt and Nickel
Magnetic induction
Magnetic induction
When a magnetic material is close to a magnet, it becomes a magnet itself
We say it has induced magnetism
NS
NSmagnet
Hard and Soft Magnetism
Soft Magnetism
Pure iron is a soft magnetic material
It is easy to magnetise but loses its magnetism easily
NS
before after
Iron nail
SN
NS
Not a magnet
N
Hard Magnetism
Steel is a hard magnetic material
It is harder to magnetise, but keeps its magnetism (it is used to make magnets!)
NS
before after
Steel paper clip
NNS
It’s a magnet!
N
S
S N
Magnetic field
I wonder if this is a magnetic
field?
Magnetic field
Magnets (and electric currents) produce magnetic fields around them.
In the magnetic field, another magnet or magnetic material will experience a magnetic force.
Magnetic field lines
We can represent the magnetic field around a magnet using field lines.
Magnetic field lines
The arrows show the direction a compass needle would point at that point in the field.
Magnetic field lines
The closer the field lines are, the stronger the magnetic force felt
The arrows show the direction a compass needle would point at that point in the field.
Earth’s Magnetic Field
N
S
Remember the North of a compass needle points to the geographic north pole (i.e. the geographic North pole is a magnetic south pole!)
Field around a bar magnet
Two bar magnets
Strong uniform field
Two bar magnets
no field!
That’s it!
Mind-map
Mr Porter is now going to put these slides on a loop and you’re going to mind-map them!
This lesson
• ac/dc
• Insulation and double insulation
• Earthing, fuses and circuit breakers
• Formative assessment
Gather round!
Reading!
• Read carefully pages 192-195
• Answer the questions on both pages
• Finish for homework due Tuesday 13th January
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