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Introduction
Magnetic and electric fields are some of
the most interesting concepts found on the
earth. The interplay between these two
things is one of the reasons that magnetic
and electric fields are used for many things
from powering motors to recording sound
and information.
Electromagnetism is also widely used in
a hospital’s equipment and is vital for the
survival of many people everyday.
Electromagnetism is essential to so many
functions of our everyday lives and to many
industries livelihoods; it is now hard to think
what life would be like without these forces.
Magnetism
The
term magnetism is
used
to
describe how materials respond on the
microscopic level to an applied magnetic
field; to categorize the magnetic phase of a
material. For example, the most well known
form of magnetism is ferromagnetism such
that some ferromagnetic materials produce
their
own
persistent magnetic
field.
However, all materials are influenced to
greater or lesser degree by the presence of
a magnetic field. Some are attracted to a
magnetic field (paramagnetism); others are
repulsed
by
a
magnetic
field
(diamagnetism); others have a much more
complex relationship with an applied
magnetic field. Substances that are
negligibly affected by magnetic fields are
known as non-magneticsubstances. They
include copper, aluminium,water,
and gases.
Electromagnetism
Is the physics of the electromagnetic
field, a field that exerts a force on charged
particles and is reciprocally affected by the
presence and motion of such particles.
A changing magnetic field produces
an electric field (this is the phenomenon
of electromagnetic induction, the basis of
operation for electrical generators, induction
motors, and transformers). Similarly, a
changing electric field generates a
magnetic field.
The magnetic field is produced by the
motion of electric charges, i.e., electric
current. The magnetic field causes the
magnetic force associated with magnets.
Electromagnetic Phenomena
With the exception of gravitation,
electromagnetic phenomena as described
by quantum
electrodynamics (which
includes as a limiting case classical
electrodynamics) account for almost all
physical phenomena observable to the
unaided human senses, including light and
other electromagnetic
radiation,
all
of chemistry, most of mechanics (excepting
gravitation), and of course magnetism and
electricity. Magnetic monopoles (and
"Gilbert"
dipoles)
are
not
strictly
electromagnetic phenomena, since in
standard electromagnetism, magnetic fields
are generated not by true "magnetic
charge" but by currents. There are,
however, condensed matter analogs of
magnetic monopoles in exotic materials
(spin ice) created in the laboratory.
Electromagnetic Force
In physics,
the electromagnetic
force is the force that the electromagnetic
field exerts on electrically charged particles.
It is the electromagnetic force that
holds electrons and protons together
in atoms, and which hold atoms together to
make molecules. The electromagnetic force
operates via the exchange ofmessenger
particles called photons and virtual photons.
The exchange of messenger particles
between bodies acts to create the
perceptual force whereby instead of just
pushing or pulling particles apart, the
exchange changes the character of the
particles that swap them.
Electromagnetic Induction
Is the production of voltage across
a conductor situated
in
a
changing
magnetic field or a conductor moving
through a stationary magnetic field.
Michael Faraday is generally credited
with the discovery of the induction
phenomenon in 1831though it may have
been anticipated by the work of Francesco
Zantedeschi in 1829].Around 1830 to 1832
Joseph Henry made a similar discovery,
but did not publish his findings until later.
History of Electromagnetism
While preparing for an evening lecture
on
21
April
1820, Hans
Christian
Ørsted made a surprising observation. As
he was setting up his materials, he noticed
a compass needle deflected from magnetic
north when the electric current from the
battery he was using was switched on and
off. This deflection convinced him that
magnetic fields radiate from all sides off of
a wire carrying an electric current, just as
light and heat do, and that it confirmed a
direct relationship between electricity and
magnetism.
At the time of discovery, Ørsted did not
suggest any satisfactory explanation of the
phenomenon, nor did he try to represent
the phenomenon in a mathematical
framework. However, three months later he
began more intensive investigations.
Discovered Electromagnetism
Michael Faraday (1791-1867)
Michael Faraday, the discoverer of
electro-magnetic
induction,
electromagnetic rotations, the magneto-optical
effect, diamagnetism, field theory and much
else besides, was born in Newington Butts
(the area of London now known as the
Elephant and Castle) on 22 September
1791. In 1805 at the age of fourteen
Faraday was apprenticed as a bookbinder
to George Riebau of Blandford Street.
During his seven year apprenticeship
Faraday developed his interest in science
and in particular chemistry. He was there
able to perform chemical experiments and
built his own electro-static machine.
Glossary
Electricity-a fundamental form of
energy observable in positive and negative
forms that occurs naturally (as in lightning)
or is produced (as in a generator) and that
is expressed in terms of the movement and
interaction of electrons
Magnets- a body having the property of
attracting iron and producing a magnetic
field external to itself; specifically : a mass
of iron, steel, or alloy that has this property
artificially imparted
Force- strength or energy exerted or
brought to bear : cause of motion or
change : active
power <the
forces of
nature> <the motivating force in her life>
Light-something that makes vision
possible b : the sensation aroused by
stimulation of the visual receptors