Applications of
magnetism
Magnetic Resonance Images (MRI)
These machines can produced up to 7 Tesla to
make very good images of the body
Q: How
to produce a strong magnetic field ?
A: Build
a giant solenoid
Q: What
is the problem with producing a strong magnetic field
A: #1
Material cannot stand the magnetic force with the magnetic field; resulting in
collapsing the material
#2
High velocity of current running through the solenoid produce a lot of heat.
This can result in melting the solenoid if the magnetic field is too strong
Super conductors
- superconductors are very useful
because it does not have any resistant with other material
- all superconductors are
diamagnetic
Animals
Animals such as sharks and
turtles can detect Earth magnetic field to know where their position and
direction around the globe (Research has not been finished, a few published
paper support this theory)
Maglev trains
WHY?
Q: Why do people invent Maglev
trains?
A:
Less friction than trains
with wheels because it does not need wheels to run
HOW?
- first it levitates using
superconductors
Q: Why do we need superconductors to levitate, why can’t we
use ferromagnetic material like the train in the demo?
A: The problem with using ferromagnetic material to
levitate the train is because ferromagnetic material will tend to want to align
itself with the opposing field. Therefore, the train will be unstable moving
right and left (i.e. like the train in the demo). The good thing about
superconductors is because they are diamagnetic. They will always oppose a
magnetic field, so they will not move out of the track trying to align with the
field like ferromagnetic materials
- After the train is levitated,
the train can move forward by the magnetic coil from the side. These coils can
flip from N to S and vice versa to attract and repel against the magnets on the
train (the magnets on the train is fixed and cannot be flipped.