2. WHAT IS MEANT BY MAGNETIC LEVITATION ?
Magnetic levitation, maglev, or magnetic suspension is a
method by which an object is suspended with no support
other than magnetic fields. Magnetic force is used to
counteract the effects of the gravitational and any other
accelerations.
3. FIRST WE HAVE TO KNOW ABOUT
Permanent Magnets
•Superconductors
Liquid nitrogen
4. Permanent Magnets
A good permanent magnet should produce a high magnetic field with a low
mass, and should be stable against the influences which would demagnetize it.
The desirable properties of such magnets are typically stated in terms of the
Remanence and Coercivity of the magnet materials
Remanence -
Remanence or remanent magnetization is the magnetization left behind in a
ferromagnetic material (such as iron) after an external magnetic field is removed. It is also the
measure of that magnetization.
Coercivity-
The resistance of a magnetic material to changes in magnetization, equivalent to the field
intensity necessary to demagnetize the fully magnetized material.
5. Superconductors-
Superconductivity is a phenomenon of exactly zero electrical resistance and
expulsion of magnetic fields occurring in certain materials when cooled below a
characteristic critical temperature. The electrical resistivity of a
metallic conductor decreases gradually as temperature is lowered. In
ordinary conductors, such as copper or silver, this decrease is limited by
impurities and other defects. Even near absolute zero, a real sample of a normal
conductor shows some resistance. In a superconductor, the resistance drops
abruptly to zero when the material is cooled below its critical temperature.
6. substance critical temperature (oC)
NH3 132
O2 -119
CO2 31.2
H2O 374
CRITICAL TEMPRATURE-Tubes
containing water at several temperatures.
Note that at or above 374oC (the critical temperature for water), only water vapor exists in the
tube
7. Liquid nitrogen -
Liquid nitrogen is nitrogen in a liquid state at an extremely low temperature.Liquid nitrogen is a
colorless clear liquid
Liquid nitrogen is the liquefied form of the element nitrogen that is commercially produced by
fractional distillation of liquid air.
Sometimes liquid nitrogen is denoted as LN2, LN, or LIN.
At normal pressure, liquid nitrogen boils at 77 K (−195.8°C or −320.4°F).
The liquid to gas expansion ratio of nitrogen is 1:694, which means liquid nitrogen boils to fill a
volume with nitrogen gas very quickly.
Nitrogen is non-toxic, odorless, and colorless. It is relatively inert. It is not flammable.
Nitrogen gas is slightly lighter than air once it reaches room temperature. It is slightly soluble in
water.
9. When we dip these supercounducting materials into the liquid nitrogen solution
10. The temperature of the super
conducting material like cu it varies
when temperature lower .when we
placed in permanent magnet it will
shows small gap between them it has
low friction.
11.
12. NOW WHAT ABOUT METRO TRAINS-It
is similar to that but we are using electro-magnetic field in metro trains
Propulsion System
•The system consists of aluminum three-phase cable windings in
the stator packs that are on the guideway
•When a current is supplied to the windings, it creates a traveling
alternating current that propels the train forward by pushing and
pulling.
•When the alternating current is reversed, the train brakes.
•Different speeds are achieved by varying the intensity of the
current.
•Only the section of track where the train is traveling is electrified.
13. This train uses superconducting electric magnets in the vehicle to levitate
and propel the train. These magnets are cooled by liquid helium or liquid
nitrogen. This means that once electrified these magnets do not require
additional energy.
•An alternating current is ran through
electromagnet coils on the guide walls of the guide
way. This creates a magnetic field that attracts and
repels the superconducting magnets on the train
and propels the train forward.
BRAKE
•Braking is accomplished by sending an alternating
current in the reverse direction so that it is slowed
by attractive and repulsive forces.
14. MagLev Pros and Cons
PROS
•MagLev is way faster than your usual bullet train. MagLevs can reach speeds up to 500 kilometres per
hour
•Due to its lack of wheels, MagLevs are quieter than normal trains, or sometimes even traffic
•MagLevs use 30% less energy than normal trains.
•A MagLev is way faster than your usual bullet train. MagLevs can reach speeds up to 500 kilometres per
hour.
•In theory, a MagLev and its track would require very little maintenance; since the train never touches the
track there is virtually no wear and tear.
Cons
•The MagLev's track is much more expensive than railroad tracks.
•Although MagLevs are pretty quiet, noise caused by air disturbance still occurs
15. Conclusion
How magnetic levitations are achieved
The maglev suspension systems
The maglev propulsion systems
