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Electromagnetic Induction and Maglev Trains

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Gogulan N

on 19 November 2013

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Transcript of Electromagnetic Induction and Maglev Trains

Electromagnetic Induction and Maglev Trains
An Attractive Alternative
Electromagnetic Induction
Maglev Trains
The Benefits of Maglev Trains over Conventional Trains
Other Uses of Electromagnetic Induction in Today’s World
What is Electromagnetic Induction?
The process in which an electric current is induced into an electric conductor by placing it in a changing magnetic field.
A current can also be generated when the electric conductor is moved through a stationary magnetic field.
How Does it Work?
Electromagnetic induction operates on three principles: electric currents have magnetic fields, alternating currents have alternating magnetic fields, and finally, changing magnetic fields cause currents to pass through conductors placed within them.
A current is induced into this conductor when it passes through a magnetic field because the magnetic lines of force place a force on the free electrons in the conductor which causes them to move.
Induction Motors:
An electric motor powered by an alternating current.
Comprise of two main parts: the stator and the rotor.
The current in the rotor creates another magnetic field within the rotor which chases the magnetic field of the stator.
Electrical Generators:
Converts mechanical energy into electrical.
Has a stator (with a magnetic field) and a rotor (created out of a coil)
To create electrical energy out of mechanical energy with a generator, we must rotate the rotor to induce a current into the stator.
What are Maglev Trains:
An extremely fast train powered by magnets that floats above its tracks.
Maglev is derived from
mag
netic
lev
itation which is the main concept in the propulsion and levitation of these trains.
Maglev trains do not touch their tracks while in motion which greatly reduces the amount of friction in the system.
Economic:
Environmental:
Efficiency:

Noise:
Speed:
Though initial costs are greater, maintenance and repair costs are much less costly.
There is no wear and there are no rails to clean or repair.
No friction so trains travel at extremely fast speeds
Only force acting against their movement is air resistance
The impact of rain or snow on these trains is very minimal.
Maglev trains accelerate and decelerate much faster than conventional trains
The maglev trains in Japan are powered solely by electromagnetic induction and magnetic fields.
Not only does this process help the trains travel at high speeds, they also do not pollute the environment as much
Most trains today are powered by diesel – a fossil fuel.
Conventional trains travel at top speeds of about 80 km/h on average. Maglev trains travel up to 300 km/h on average.
By travelling on trains that go this fast, commuters are able to reach their destinations much faster
The main source of noise in maglev trains comes from the displacement of air.
In conventional trains, the main source of noise comes from the screeching of the wheels and the rails.
Since the maglev trains levitate, there is no contact between the train and track. This creates a much quieter ride.
Michael Faraday
:
English scientist who had greatly contributed to the field of electromagnetism.
Discovered electromagnetic induction
Faraday had wrapped two separate, insulated coils of wire around a metal ring and discovered that by generating a current in one wire, another electric current was momentarily induced in the other.
Faraday’s Law of Electromagnetic Induction states: “An electric current is induced in a conductor whenever the magnetic field in the region of the conductor changes with time.”
A Bit of History:
Michael Faraday and Joseph Henry first discovered electromagnetic induction in 1831.
In this investigation, Faraday connected one wire to a battery and another to a galvanometer (a device that measures small electric currents).
He concluded that this wave of electricity was generated due to a change in the magnetic flux (the strength of the magnetic field over a given area) when he connected and disconnected the battery.
Tried to use "lines of force" to explain his theory.
Lenz's Law:
Heinrich Lenz was another great scientist who had greatly contributed to electromagnetism. He discovered how to determine the direction of the induced current in 1834 using the law of conservation of energy.
He believed that when the magnetic field of a moving magnet induces a current in a coil, the new current generates another magnetic field which he calls the “induced” field.
Lenz’s Law states: “When a current is induced in a coil by a changing magnetic field, the electric current is in such a direction that its own magnetic field opposes the change that produced it”
The work done in overcoming the opposing induced field and pushing the magnet into the coil is transformed into electrical energy in the coil.
History of the Maglev Train:
Maglev trains were initially designed to eliminate the large amounts of friction between the wheels of high speed trains and the rails.
After the discovery of superconductors, maglev trains garnered a lot more interest than ever before. Conventional magnets were replaced by superconducting magnets.
Through his discovery of the linear induction motor, Eric Laithwaite developed the first ever commercial maglev vehicle and was later known as being the “father of maglev.”
A linear motor is essentially an electric motor with its stator and rotors “unrolled.”
The world’s first high-speed commercial maglev train was unveiled in Shanghai in 2004.
How They Work:
Maglev trains operate on the principle of electromagnetic induction. Although all maglev trains are designed to do the same task, there are two different ways in which they operate.
The Germans used EMS (electromagnetic suspension) whereas the Japanese used EDS (electrodynamic suspension).
In EMS, electromagnets are placed on the cars to lift them off the track while the tracks are lined with coils.
To further stabilize these trains, there are lines of guidance magnets placed on the sides of the undercarriage.
These trains claim to reach speeds of up to 438 km/h.
In EDS, very cold, superconducting magnets are placed on the trains while the tracks are lined with electromagnetic coils.
Unlike the EMS method, they are able to conduct electricity even after the power supply has been cut off.
There are two sets of coils: guidance/levitation coils and propulsion coils.
Since the electric current is constantly alternating, the polarity of the electromagnets is also changing.
By: Gogulan Navathasan
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