Electromagnetic Waves and Radio

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4/12/06 Electromagnetic Waves and Radio

• Poster Session Meetings
• Schedule appointment
• Change/Modify your topic
• Plan your poster
• Etc.

• Fridays Reading
• Section 13.2 Microwave Ovens (pp. 432 438)
• Upcoming Reading Assignments
• Section 14.1 Sunlight (pp. 445 453)
• Section 14.2 Discharge Lamps (pp. 454 463)
• Section 14.3 Lasers and LEDs (pp. 464 470)
• Section 15.1 Cameras (pp. 478 488)
• Section 15.2 Optical Recording and Communication
  (pp. 489 497)

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• Types of Memory
• Magnetic (information stored in orientation of
  poles)
• Flash (information stored in charge on
  transistors floating gates)
• Optical (discuss later in course)

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Electric and Magnetic Fields Sources of Electric
Field? Sources of Magnetic Field? Accelera
ted Charges
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Electromagnetic Waves Electromagnetic Spectrum
Figure from Tipler Mosca, Physics for
Scientists and Engineers, 5th edition, p. 977
Exercise Visible light is a small portion of
the electromagnetic spectrum. The wavelengths of
visible light range from 400 nm (violet) to about
780 nm (red). What is the range of frequencies
of visible light? (1 nm 10-9 m)
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Direction of EM Waves Polarization
EM wave made up of Electric field and Magnetic
field E perpendicular to B Direction of wave
perpendicular to E and B
Exercise The Electric field part of an EM wave
oscillates IN and OUT of the screen. What are
possible directions of the Magnetic field part of
this EM wave?
Follow-up Exercise An EM wave is moving to the
LEFT. At some instant at some point, the
Electric field points OUT of the screen. At this
instant at this point, what is the direction of
the Magnetic field?
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Making a Radio Wave