Episode: Magnetic Homer Starring Mayank Gulati Jagseer Natt
Pulkit Gulati THE SIMPSONS
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Magnet Concepts Magnetic Fields of Conductors Domain Theory
Magnetic Force on Conductors Electromagnetic Induction Magnetic
Force on Moving Charges
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Magnetic Fields of Conductors Electromagnets Electric current
flowing through wires creates magnetic fields in circles around the
wire, perpendicular to the wire based on the right hand rule. When
wire is coiled around in circles and then current is applied, all
of the segments of the wire create fields that can add up to
virtually act as a bar magnet. The straightness and strength of the
solenoids field lines depends on the tightness of the coiled wires
and the amount of current flowing through, with the field being the
strongest at the center of the loops. The direction of the field is
determined similarly using the right hand rule, perpendicular to
individual wires. The biggest advantage of such electromagnets is
the level of control of strength and even the ability to turn it
off.
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Domain Theory Fridge Magnets Ferromagnetic substances are made
of many tiny magnetic domains, each acting like its own bar magnet.
When the substance is not magnetic, all of the domains are in
random orientations with none dominating. But if the substance is
placed in a strong enough magnetic field, the domains can rotate
and align with the external field. This causes the material to
behave like a magnet. When the external field is removed, whether
or not the orientation will remain, depends on the material. If the
orientation remains the material becomes a permanent induced
magnet, whereas if it returns to random order, the material was
only a temporary magnet. Many metals display such properties and
are attracted to magnetic material. If a paperclip is on a magnet,
it itself can act as attract others.
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Magnetic Force on a Conductor Maglev Trains Magnetic fields
apply forces to conductors that have a current running through them
and are submerged in a magnetic field as described by the equation
Where F is the magnitude of the force acting on the conductor I is
the current in the conductor l is the length of the conductor B is
the magnitude of the magnetic field is the angle between the
conductor and the field lines This force is in the direction as
determined by the right hand rule with respective directions being
the North to South field lines and conventional current flow.
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Although steady current can produce a steady magnetic field, a
steady magnetic field cannot directly induce a current in a
conductor. Electric current in conductors is actually induced by
the change in a magnetic field, known as the law of electromagnetic
induction. Currents can be produced in loop of wire rotated in
uniform magnetic field and connected to galvanometer in ammeter
configuration. If a permanent magnet is passed through loops of
wire, as the wires experience the change in the field around them,
they will have current. Electromagnetic Induction Electric
Generator Coil The induction occurs in conductors perpendicular to
the field, not parallel.
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With the knowledge that current acts upon magnetic fields
(specifically, a wire with current can create a magnetic field),
Newtons third law dictates that a magnetic field must also act upon
Current, or moving charges In a magnetic field, moving charged
particles experience a centrifugal force to the component of their
velocity perpendicular to the field. The force only changes the
direction and not the magnitude of the velocity, thus it only works
when the charges are moving, or if current exists. Magnetism on
Moving Charges Television Tubes
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Particle Collider Mass Spectrometer 686F6D65
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Particle Colliders accelerate protons to near light speed and
collide them to study the true building blocks of matter and other
advanced theorems. Although electrostatic forces are used to
actually accelerate these particles, since the tube travelled by
the proton is a circle, magnets are used to steer these particles
in the right direction. Particle Colliders Forces on Moving
Charges
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A mass spectrometer is used to split a sample into its various
ions based on the mass of the ion. This is done by charging the
sample and passing it through a field Since the force of a magnet
on charged particles is a centrifugal force dependant on the
mass/charge ratio, the uniformly charged ions split up based on
their mass as they pass through the field. This is demonstrated in
the picture Mass Spectrometer Forces on Moving Charges
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Anti-Lock Brake System Speakers Televisions Fridge Magnets
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ABS is a safety feature in all modern cars that ensures highest
traction of tyres while breaking by computerizing the pressure
control of a brake pad To do this, the system must keep an accurate
measure of every individual wheels instantaneous speed without
actually touching the wheel and creating friction. This is achieved
by monitoring field fluctuations created by magnetic teeth mounted
around the wheel. Anti-Lock Braking System Magnetic Field
Detection
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Attraction and repulsion Speakers need to create vibration in
the air to produce sound, done by pushing and pulling the cone. The
force behind this is magnetic attraction and repulsion An
electromagnet interacts with a permanent magnet, where alternating
current can create different polarities in the electromagnet,
causing the permanent magnet to be pulled and pushed at the
frequencies of the sound required. Speakers
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CRT televisions work by firing electrons on a coating that
glows certain colors upon being hit. Since there is only a limited
number of electron guns in a TV, powerful electromagnets are used
to steer these electrons Controlled magnets can accelerate the
electrons to hit just the right part of a film to create the color
needed as they are fired, at up to 60Hz. If an external magnet is
brought close to an older CRT TV, color distortion can be easily
seen Television Tubes Forces on Moving Charges
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Ferromagnetism Fridge magnets are the most common use of
ferromagnetism, using magnetic materials to stick to a steel
refrigerator. Though these are not constructed the same as normal
magnets Constructed in the Halbach array arrangement, fridge
magnets alternate poles as north and south. This effectively gives
the back side double the magnetic strength in the same surface
area, while eliminating the field on the front side. This can be
easily felt when rubbing it with regular magnets. Fridge
Magnets
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Generator Transformers Nuclear Fusion
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Nuclear Fusion is a very powerful way of planned electric
generation, and is currently prototyped in a doughnut shaped
enclosure filled with hot ionized plasma to accelerate particles To
easily control both the hot ionized plasma and the particles
involved in fusion; wires can be wrapped around the enclosure to
induce an electromagnetic field within it; thus successfully
navigating the plasma using centrifugal force. Forces on Moving
Charges
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Electric Generator Coil Electromagnetic Induction Using
electric generation coil is the method of producing electricity in
most all ways including hydro, coal, wind and any other
turbine/rotating technology This works based by having conductive
coils spin in a magnetic field where the magnets can induce AC into
the coil. In a circle, since the two sides move in opposite
direction, the induced voltages at the ends add. The actual amount
of induced voltage is based on Faradays Law
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Transformers Michael Faraday A transformer can be used to
step-up or step-down electrical voltage to change from high
generation voltages to residential use voltages of 120V in the
electrical grid. It works by having two sets of coils wrapped
around an iron core, with the output voltage depending on the
amount of wire on one end relative to the other. The AC current in
the input induces a changing magnetic field, allowing induction of
current on the other end at different voltages.
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Super Conductivity Developed in the 1970s, MRI machines use
strong magnets and radio frequencies to alter magnetic alignments
of bodily atoms. As the protons return to their normal
electromagnetic spin at different rates, medical imaging can be
produced This magnetic field can be as strong as 2 Teslas, created
using superconductors cooled to create almost no resistance,
allowing current to create the strongest of magnets. Magnetic
Resonance Imaging
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Aurora Lights The charged particles stay in place as the
changing strength of the earths field creates a magnetic mirror. As
the atmospheric particles collide with these charges, they release
photons creating the magnificent northern and southern lights.
Charged particles from solar winds spiral around the earths
magnetic field lines until they collect up near the north and south
poles. Forces on Moving Charges
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Earths Magnetic Field William Gilbert Sir William Gilbert
described Earths magnetic field as a large bar magnet at a slight
angle to the earths axis. This fairly weak field enables compasses
and protects the earth from solar winds Although it is not
completely understood how the field is created, it is theorized to
be induced by the rotation of the liquid iron inside of the earths
core creating magnetic phenomenon about its axis.
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Diamagnetism All matter has slight tendencies to create a
magnetic field opposite to an externally applied one, causing
repulsion. This repulsion is regardless of the polarity of the
field. Paramagnetism/ Ferromagnetism This occurs due to the orbital
velocity of electrons around their nuclei, changing the magnetic
dipole moment when in a field. According to Lenz's law, this
opposes the external field. And thus all matter, even water, is
slightly repulsive to all magnets
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Generally Regarded as the father of magnetism and electricity,
being an astronomer, Gilbert discovered the earths natural magnetic
field. This explained how a compass needle works and debunked many
other theories. William Gilbert (1540-1603) Earths Magnetic
Field
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Coulomb studied electrostatic forces, attraction and repulsion
between charged objects. He found that this depends on the inverse
square of the distance and directly on the charges itself. this is
called the Coulombs Law and is the basis for all electrostatic
applications today Charles De Coulomb (1736-1806)
Electrostatics
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While studying magnetism, faraday discovered the basis of
electromagnetic fields, induction, diamagnetism, electrolysis and
the interaction of light and magnetism. Faradays ring, his
invention using varying coils of wire around an iron ring to change
voltage was the first working transformer. Michael Faraday
(1791-1867) Electromagnetic Induction
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Found the right hand rule of direction of induced current as
perpendicular to the magnetic field lines, or that it opposes the
change causing it. This is called the Lenz Law and demonstrates how
electromagnetic circuits always follow Newtons third law. Heinrich
Lenz (1804-1865) Lenz Law
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James Clerk Maxwell (1831-1879) Best known for formulating the
classical electromagnetic theory, uniting electricity, magnetism
and light as one in Maxwells equations, he has been called the
father of modern physics. He also proved that electromagnetic
fields (and thus light) can self sustain and travel through space
as waves. Maxwells Equations
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Maglev Trains Magnetic Levitation Trains use various
technologies such as flux tunnels created by superconductors or
special arrays of magnets set up to both repel/levitate the train
off the tracks and attract/propel it forwards. This achieves two
things: Eliminating friction to make acceleration easier, and
creating movement from powerful electromagnets for much faster
speeds. Magnetic and Dynamic Suspension
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MDH - Yamato 1 Created in 1991 by The Japanese Mitsubishi
Group, the Yamato 1 is the first boat to successfully propel itself
without using any moving parts It does by applying magnetic fields
to electrically conductive liquid, seawater. The force that the
magnetic field applies on these moving charges pushes the boat
forward. This is known as MDH propulsion. Forces on Moving
Charges