Electromagnetism is a stunningly powerful
idea. In fact. our lives would be unrecognizable without it. It is all about
what happens when you combine electric charges, movement, and magnetic fields.
Move a metal wire within a magnetic field, and you will cause an electric
current to flow in the wire. This is how we generate electricity. Conversely, send
an electric current through a wire, and the movement of electric charges will
create a magnetic field. This is how we make the electromagnets that power most
doorbells and particle accelerators. The third option is to run an electric
current through a wire sitting in a magnetic field. The wire will move. This is
the idea behind the electric motor in your kitchen whisk and power drill.
The main credit for the theory rests with a Scotsman, James Clerk
Maxwell, who first wrote down the equations that describe the complex interplay
of electric and magnetic fields. The equations, it turned out. required an
unexpected factor: the speed of light. This revelation led to the understanding
that light and radiant heat can be thought of as moving variations in
electromagnetic fields. These moving fields came to be known collectively as radiation.
Investigations of radiation led Max Planck to invent quantum theory and
Albert Einstein to come up with his concept of relativity.
by Michael
Brooks, 30 Second Theory
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