James Clerk Maxwell, a Scottish physicist
and mathematician, is generally regarded as one of the world's greatest
physicists. Maxwell's researches combined the fields of electricity and
magnetism and introduced the concept of the electro-magnetic
field. Following James Clerk Maxwell's research, we now call a space
modified by the presence of magnetic field lines a "magnetic field": if
a bar magnet is placed there, it will experience magnetic forces, but the
field exists even when no magnet is present. Similarly, an "electric field"
is the space in which electric forces may be sensed--for instance between
metal objects charged (+) and (-) by a battery, as in the drawing accompanying
the discussion of the electron.
In 1864, James
Clerk Maxwell demonstrated a subtle connection between the two types of
force, unexpectedly involving the velocity of light. James Clerk
Maxwell showed that an "electromagnetic wave" was possible, a rapid interplay
of electric and magnetic fields spreading with the velocity of light. Maxwell
correctly guessed that light was in fact such a wave, that it was basically
an electromagnetic phenomenon, and with this his equations paved the way
to a much deeper understanding of optics, the science of light. He further
showed that electric and magnetic fields travelled through space, in the
form of waves, at a speed of 3.0 × 108 m/s. He thus argued that light
was a form of electromagnetic radiation.
James Clerk Maxwell predicted the
existence of radio waves. From this connection sprang
the idea that light was an electric phenomenon, the discovery of radio
waves, Einstein's theory of relativity and
a great deal of present-day physics.
with > The
History of Radio or Magnetic
Fields : History