3B Scientific Diamagnetic Levitation Apparatus - Manual

4
Instruction Sheet
3B SCIENTIFIC 3B SCIENTIFIC 3B SCIENTIFIC 3B SCIENTIFIC 3B SCIENTIFIC® PHYSICS PHYSICS PHYSICS PHYSICS PHYSICS
®
U45051 Diamagnetic Levitation Apparatus
1/04 ALF
1 Base plate
2 Plastic bell housing
3 Plastic plate
4 Graphite plate
5 NdFeB-magnet
6 Retaining ring
7 Hex nut
8 Ring magnets
1
2
3
4
5
6
7
8
7
The Diamagnetic Levitation Apparatus allows the dem-
onstration of the mode of action of diamagnetic ma-
terials.
1. Safety instructions
•
Keep all the magnets away from electronic equip-
ment, magnetic media and delicate instruments.
•
The ring magnets are brittle and may break if
dropped.
•
The graphite plate are easily broken or scratched.
Handle with care.
•
The cube shaped magnet is very brittle and may
break merely by flying to the ring magnets.
•
Use only finger pressure to tighten the hex nuts.
•
If needed clean only with mild dish soap. Do not
use abrasive cleaners or solvents.
2. Description, technical data
Within a plastic bell housing there are two graphite
plates. Between these plates a cubic shaped NdFeB-
magnet, plated with 24K gold, levitates freely. The gravi-
tational force acting on the magnet is almost entirely
counteracted by the force of attraction from a ring
magnet located above the plastic covering. The two
diamagnetic graphite plates, one above and one be-
low the NdFeB magnet, compel it into a stable equi-
librium since both poles of the magnet are repelled by
the graphite plates (diamagnetism).
Dimensions:
Base plate:
95 mm x 95 mm
Height: 135 mm
2.1 Scope of delivery
1 Levitation apparatus
2 Transparent plastic plates
1 Socket wrench
3. Theory
The physicist S. Earnshaw proposed the following theo-
rem in 1848: it is not possible for charges or magnets
to be placed in a stable levitated state in a static field
obeying an inverse square law. He further stated, how-
ever, that it would be possible to achieve this with the
help of diamagnetic materials.
The availability of very powerful rare-earth metal mag-
nets has made it possible to design a levitation appa-
ratus such as this using graphite as the diamagnets.
Diamagnetic materials are repelled from both magnetic
poles.
The action of this levitation apparatus may be under-
stood in terms of either forces, or potential energy.
The force of earth's gravity pulls downward on the cube
magnet, while the ring magnets exert an upward force.
The position of the ring magnets is chosen in such a
way, that the two forces equal each other. If the gravity
is stronger than the force of attraction, the cubic mag-
net will fall down. In the opposite case it will move
upwards.
The diamagnetic property of graphite effects the cubic
magnet in such a way that it is repelled from the re-
spective plate. This force is tiny but it is enough to sta-
bilize the NdFeB-magnet in a state of stable equilib-
rium.
To get a deeper understanding of the state of equilib-
rium we look at the potential energy of the cubic mag-