This document summarizes magnetic levitation (Maglev), which uses electromagnetic forces to levitate objects without physical contact. It describes how Michael Faraday discovered magnetic fields and Heinrich Lenz discovered the direction of magnetic forces. Faraday's law and Lenz's law explain how changing magnetic fields induce currents that can produce levitation. Methods like using diamagnetic materials, electromagnets in a feedback loop, and rotational stabilization are described. Applications discussed include Maglev transportation, bearings, toys, and effects like noise pollution from Maglev trains.

1. MAGNETIC LEVITATION
Presented By
Amey Mithsagar

2. What is it?
Magnetic Levitation , often abbreviated as “MagLev” is a
technique by which an object can be made to float in air with the
help of Electromagnets.

3. Invention
The discovery of Magnetic Fields around a magnet was made by
Michael Faraday.
The direction of forces created by Faraday’s Law was discovered
by Heinrich Lenz.
The phenomenon of a body levitating mid-air was discovered as
early as 1934.
Michael Faraday Heinrich Lenz

4. Faraday’s Law
• This law states that if there is a change in the magnetic field
on a coil of wire, there is seen a change in voltage.
• The figure below shows that a change in magnetic field
produces current.
• For the purposes of magnetic levitation the ability to change
the strength of a magnetic field by just changing the current is
powerful. If there is a need for more of a force, then sending
more current through a coil of wires will produce more of a
greater magnetic force.

5. Lenz’s Law
• His theory states that “the emf induced in an electric circuit
always acts in such a direction that the current it drives
around the circuit opposes the change in the magnetic flux
which produces the emf”.
• The application that this has on magnetic levitation is that this
will allow the direction of the magnetic field to be predictable
and thus a set up can be created for a specific purpose to
maximize the force that is created.

6. How does it work
Magnetic Levitation works on the principle of repulsion.
The Magnetic force produced, repels gravity under it’s field of
influence. This helps the body to suspend in mid-air without any
visible supports.

7. Stability
Stability of a Magnetic Levitation system is defined as the
property by which the body can remain stable in the influence of
the magnetic field.
The Earnshaw’s theorem forms the base of stability.

8. Earnshaw’s Theorem
Earnshaw’s theorem states that a collection of point charges
cannot be maintained in a stable stationary equilibrium
configuration solely by electrostatic interaction of charges.
This theorem was put forth by British mathematician Samuel
Earnshaw in 1842.
𝛻 ∙ 𝐹 = 𝛻 ∙ −𝛻𝑈 = −𝛻2 𝑈 = 0
In mathematical notation, an electrical force F(r)
Deriving from a potential U(r) will always be divergenceless.

9. Static Stability
Static stability means that any small displacement away from a
stable equilibrium causes a net force to push it back to the
equilibrium point.
Diamagnetic materials are stable along at least along one axis.
While it can be made stable along other axes.

10. Dynamic Stability
Dynamic stability occurs when the levitation is able to damp out
the any vibration-like motion that may occur.
Due to absence of damping, vibration modes cause the body to
leave the stable region.

11. Methods of Magnetic
Levitation
For successful levitation and control of all 6 axes, a combination
of permanent magnets and electromagnets or diamagnets or
superconductors as well as attractive and repulsive fields can be
used. From Earnshaw's theorem at least one stable axis must be
present for the system to levitate successfully, but the other axes
can be stabilized using ferromagnetism.

12. Pseudo Levitation
This method uses a form of mechanical constraint to attain
stability.
A mechanical constraint can be a string or cable.
Mechanical constraint (in this case the lateral
restrictions created by a box) can permit pseudo-
levitation of permanent magnets

13. Servomechanisms
Stable magnetic levitation can be achieved by measuring the
position and speed of the object being levitated, and using
a feedback loop which continuously adjusts one or more
electromagnets to correct the object's motion, thus forming
a servomechanism.
This forms the base of Electromagnetic suspension.

14. Diamagnetically Stabilised
Levitation
• Earnshaw’s theorem is redundant for diamagnets.
• These behave in the opposite manner to normal magnets
owing to their relative permeability of μr < 1 .
• Diamagnetic Levitation can be stable on it’s own.

15. Direct Diamagnetic Levitation
A diamagnetic substance repels a magnetic field.
As water is predominantly diamagnetic, this technique has been used
to levitate water droplets and even live animals viz. frogs, mice, etc.
Since high magnetic fields are required for this, any ferromagnetic
material nearby can cause a lot of problem.
A live frog levitates inside
a 32 mm diameter vertical
bore of a Bitter
solenoid in a magnetic
field of about 16 teslas

16. Rotational Stabilisation
• A magnet with a toroidal field can be stably levitated against
gravity when gyroscopically stabilised by spinning it in a
second toroidal field created by a base ring of the magnet.
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17. Uses
Due to the inherent property of levitation, a combination of
electromagnets can be used for varied purposes.
These range from transportation to toys.

18. Transportation
It is a system of transportation that suspends, guides and propels
vehicles, predominantly trains, using magnetic levitation from a
very large number of magnets for lift and propulsion.
This method has the potential to be faster, quieter and smoother
than wheeled mass transit systems. The technology has the
potential to exceed 6,400 km/h (4,000 mi/h) if deployed in
an evacuated tunnel.
The Shanghai MagLevWorking of MagLev

19. Bearings
A magnetic bearing is a bearing that supports a load using magnetic levitation.
Magnetic bearings support moving parts without physical contact. For instance,
they are able to levitate a rotating shaft and permit relative motion with very low
friction and no mechanical wear. Magnetic bearings support the highest speeds of
all kinds of bearing and have no maximum relative speed.

20. Toys
Magnetic Levitation can be used as a fun tool for kids.
Reputed international fast food chains are employing this
technique to produce toys. These toys range from comic book
figures to action heroes’ scale models.
These are the main attractions nowadays, due to which the fast
food industry is flourishing.
A magnetically levitated toy

21. Social Effects
• The environmental effects of Maglev Trains is noise pollution and
the land that gets damaged.
• There is a huge financial problem with Maglev Trains. The cost of
guide rail is very high and the current track used cost about $39
million per kilometre. The Chinese government estimated the cost
of building and extension to the Maglev line will cost $25 million per
kilometre.
• The positive aspect to the maglev train is it produces less Co2
emissions compared to other vehicles.
CO2 Emissions’ Chart

22. Fun Facts
• First ideas of maglev: Early 20th Century(1939, to be precise)
• First maglev train suitable for passengers: Transrapid 05
(Germany) 1979
• Fastest maglev speed: 581 km/h at Yamanashi Test Line, Japan
(2003)
Guiness World Record authenticated.
• First commercial maglev: Shanghai Maglev Train
• Cost to build the maglev: 10 billion CNY (1.5 billion USD)
• Years to build the maglev: 3
• Time it takes to travel 30 km from the airport to downtown
Shanghai: 7 min 20 s

23. THANKYOU!