Key Terms
EXAMPLE
E-field of 1000 V/m gives B = 1000 / (3.00 x 10^8) = 3.33 x 10^-6 T. That's less than one-tenth of Earth's magnetic fiel
All EM waves obey
C = f * lambda
Note
Exceptions exist (MRI is one; see below).
AM Radio
540 to 1600 kHz
FM Radio
88 to 108 MHz
TV (VHF)
54-88 MHz and 174-222 MHz (video = AM, audio = FM)
TV (UHF)
470-1000 MHz Cell phones: ~1.9 GHz
How microwave ovens work
2.45 GHz microwaves cause polar molecules (like water) to continuously reorient with the alternating E-field. This absor
Radar
Detects objects by timing microwave echoes. Doppler shift in the echo reveals object speed.
Deep space background
2.7 K blackbody radiation from the Big Bang remnants, detected by Penzias and Wilson (1964), peaks in the microwave rang
Health effects of UV-B
Skin cancer, cataracts, DNA damage (distorts double helix), immune suppression. Tanning is a defense mechanism (pigment
Benefits
Vitamin D synthesis (UV-B), sterilization, fluorescence analysis, treating jaundice.
Given
Power P, area A Find: I, E-0, B-0