Frequency of a Microwave Oven

The Physics Factbook
Edited by Glenn Elert -- Written by his students
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Bibliographic Entry Result
(w/surrounding text)
Serway & Faughn. College Physics. 4th ed. USA, 1995: 687. "Microwaves have wavelengths ranging between about 1 mm and 30 cm." 1–300 GHz
The World Book Encyclopedia of Science: Physics Today. World Book, 1989: 95. "… about 2.4 × 109 Hz" 2.4 GHz
Speed of Light With Marshmallows. Virtual Prof's Bulletin Board for Teachers. Posted by Robert Stauffer on July 26, 1997 at 21:34:28. "Most commercial microwaves operate at 2450 MHz." 2.45 GHz
Finkenthal, Daniel; et al. Introduction to the Electromagnetic Spectrum. General Atomics Fusion Education. "Your microwave oven operates at a frequency of 2.45 GHz (gigahertz)" 2.45 GHz

I will start by defining several terms. Wavelength is the horizontal length of one cycle of a periodic wave. It is also the horizontal distance between two successive crests, two successive troughs, or any two successive equivalent points on the wave. Frequency is the number of cycles per unit of time. The unit of frequency is a hertz (Hz). Velocity is a vector concept that deals with the direction and speed of an object.

I found that in a typical microwave oven, the frequency is about 2450 MHz. Using the formula, velocity = frequency x wavelength and knowing that the velocity of an electromagnetic wave is about 3.0 × 108 m/s, gives a wavelength of about 12 cm.

In many ways, microwaves resemble radio waves but they are more difficult to generate. Microwaves can be concentrated into powerful, highly directional beams and are widely used for satellite communications.

Howard Cheung -- 1998

Bibliographic Entry Result
(w/surrounding text)
McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Fireside, 1984: 614. "Here is how a microwave oven works: a transmitter, very much like a radio transmitter, sets up an electromagnetic field in the oven which reverses its polarity some 2 or 5 billion times every second (it operates at a frequency of either 915 or 2450 millioncycles per second, compared to wall socket currents at 60 cycles, and FM radio signals at some 100 million cycles per second)." 0.915 or 2.45 GHz
Brain, Marshall. How Microwave Ovens Work. "In the case of microwave ovens, the commonly used radio wave frequency is roughly 2,500 megahertz (2.5 gigahertz)." 2.45 GHz

Editor's Supplement -- 2001

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