4/12/06

Electromagnetic Waves and Radio

Friday’s 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)

Poster Session Meetings

•Schedule appointment

•Change/Modify your topic

•Plan your poster

•Etc.

Types of Memory

• Magnetic (information stored in orientation of poles)

• Flash (information stored in charge on transistor’s “floating gates”)

• Optical (discuss later in course)

Electric and Magnetic Fields

Sources of Electric Field? Sources of Magnetic Field?

Accelerated Charges

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)

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?

vBE

Making a Radio Wave