JMU
Electric and Electromagnetic (EM) Waves
An Introduction


Prof. David Bernstein
James Madison University

Computer Science Department
bernstdh@jmu.edu


Electricity Basics
Electricity Basics (cont.)
Electricity Basics (cont.)
Electromagnetism Basics
Electromagnetism Basics (cont.)

A charge, \(q\), moving with velocity, \(v\), in an electric field, \(E\), and magnetic field, \(B\), experiences a force called the Lorentz force (or electromagnetic force) of:

\(F = qE + qv \times B\)

images/electric-current_force.gif
Pulses
Observations About Electromagnetic Pulses
Electromagnetic Waves

An Illustration

images/em-wave.gif
Electromagnetic Waves (cont.)
Electromagnetic Waves (cont.)
The Electromagnetic Spectrum

International Telecommunication Union (ITU) Bands

Band Frequency
Gamma Rays 1022
1021
1020
1019
1018
1017
X-Rays 1016
Ultraviolet 1015
Visible Light 1014
Infrared 1013
THF 1012 (1THz)
EHF 1011
SHF 1010
UHF 10 9 (1GHz)
VHF 10 8
10 7
High 10 6 (1MHz)
Medium 10 5
Low 10 4
Very Low 10 3 (1KHz)
10 2
Extremely Low 10 1
10 0 (1Hz)