22.9 Electromagnetic Waves (continued)

Electric and Magnetic Properties

Maxwell's Equations, using values for ordinary electric and magnetic properties that are easily measured in the laboratory, predicted the speed of an electromagnetic wave in vacuum, labeled as c, to be

c =

eo and µo describe the electrical and magnetic characteristics of a vacuum&endash;or free space.

eo = 8.85 x 10 - 12 C2/(N m2)

and is called the permittivity of free space and

µo = 4 x 10 - 7 T m/A

and is called the permeability of free space.

These words, "permittivity" and "permeability", sound strange because they are new to you. You might feel more comfortable now if, historically, these had been described as "eo is the electric characteristic of free space" and "µo is the magnetic characteristic of free space". That is all they are.

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(c) Doug Davis, 2003; all rights reserved