Do now!
Do you know the formulae for Wenesday’s Test?
D = m/Vp = F/Ap = ρhg
p1V1 = p2V2 (constant temp and fixed mass)
p1/T1 = p1/T1 (constant volume and fixed mass)
Henry (aged 8¾)
What do you need to know about 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 fields
I wonder if this is a magnetic
field?
Magnetic fields
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.
Mind-mapMs Weston will put these slides on a loop and you are going to mind-map
them
(Colours, drawings,
single words)
Plotting magnetic fields
Plotting magnetic fields
Plotting magnetic fields
Plotting magnetic fields
1. Two magnets, opposite poles facing each other 6 cm apart
2. Two magnets, like poles facing each other 6 cm apart
3. Two magnets along side each other, 5 cm apart, opposite poles opposite each other.
Field around a bar magnet
Two bar magnets
Strong uniform field
Two bar magnets
no 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!)
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