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Introduction
Electromagnetism is the physics of the
electromagnetic field, a field that exerts a
force on particles with the property of
electric charge 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.
Electromagnetism
Electromagnetism is responsible for
interactions between charged particles
that occur because of their charge and for
the
emission
and
absorption
of photons (electromagnetic radiation).
The
phenomena
of
electricity and magnetism are
consequences of this force, and the
relationships between them were first
described by James Clerk Maxwell in the
1860s.
The
physical
description
of electromagnetism has since been
combined with quantum mechanics into
the
theory
of
quantum.
The
electromagnetic force is about 1036times
as strong as the gravitational force , but
significantly weaker than both the weak
force and the strong force.
History of
Electromagnetism and
Magnetism
While preparing for an evening lecture on
21 April 1820, Hans Christian Ørsted
developed an experiment that provided
surprising evidence. 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, Oersted did not
suggest any satisfactory explanation of
the phenomenon, nor did he try to
represent the phenomenon in a
mathematical framework.
Electromagnet
An electromagnet is a piece of wire
intended to generate a magnetic field with
the passage of electric current through it.
Though all current-carrying conductors
produce magnetic fields, an
electromagnet is usually constructed in
such a way as to maximize the strength of
the magnetic field it produces for a special
purpose. Electromagnets find frequent
application in research, industry, medical,
and consumer products.
Technological uses of
electromagnetism
Before the advent of technology,
Electromagnetism was perhaps most
strongly experienced in the form of
lightning, and electromagnetic radiation
in the form of light. Ancient man kindled
fires which he thought were kept alive in
trees struck by lightning.
Much of the magic of nature has been put
to work by man, but not always for his
betterment or that of his surroundings.
Electricity at high voltages can carry
energy across extended distances with
little loss. Magnetism derived from that
electricity can then power vast motors.
But electromagnetism can also be
employed in a more delicate fashion as a
means of communication, either with
wires (as in the telephone), or without
them (as in radio communication
Discovered the
Electromagnetic
James Clerk Maxwell (13 June 1831
– 5 November 1879) was a Scottish
theoretical physicist and mathematician.
His most important achievement was
classical
electromagnetic
theory,
synthesizing all previous unrelated
observations, experiments and equations
of electricity, magnetism and even optics
into a consistent theory.[1] His set of
equations—Maxwell's
equations—
demonstrated that electricity, magnetism
and even light are all manifestations of the
same phenomenon: the electromagnetic
field. From that moment on, all other
classic laws or equations of these
disciplines became simplified cases of
Maxwell's equations.
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 c : electromagnetic
radiation
of
any
wavelength that travels in a vacuum with a speed of
about 186,281 miles (300,000 kilometres) per
second; specifically : such radiation that is visible to
the human eye