Definitions of Hertz, Kilohertz, etc.
This article defines and compares frequency measurements expressed in Hertz, Kilohertz kHz, Megahertz MHz, Gigahertz GHz, and Terahertz THz .
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Relation of wavelength to frequency & speed: notice that the shorter the wavelength the higher the frequency. That's why in our table above as the wavelengths get smaller (notice those negative exponents?) the electromagnetic frequency numbers get larger.
More technically, wavelength is inversely proportional to wave frequency.
Do not confuse wavelength and frequency of an electromagnetic wave with its speed.
All electromagnetic waves move at or close to the speed of light (and do move at the speed of light if measured in a vacuum).
The speed of an electromagnetic wave, expressed in meters per second is equal to wavelength (in meters) x frequency (in oscillations per second or Hertz, abbreviated as Hz).
Our table (below) provides definitions of various frequencies or oscillation rates expressed in kilohertz, megahertz, gigahertz, or terahertz.
Frequency Definitions | Frequency in words | Frequency in Exponent Form |
---|---|---|
Definition of Hertz Hz | One Hertz - one cycle per second | 10-1 |
Definition of Decahertz daHz | Tens of cycles per second | 101 |
Definition of Hectohertz hHz | Hundreds of cycles per second | 102 Not in common use |
Definition of Kilohertz KHz |
One kilohertz - one thousand cycles per second = 1,000 | 103 |
Definition of Megahertz MHz |
One megahertz - one million cycles per second = 1,000,000 | 106 |
Definition of Gigahertz GHz |
One gigahertz - one billion cycles per second = 1,000,000,000 | 109 to 1012 (range) |
Definition of Terahertz THz |
One terahertz - one trillion of cycles per second = 1,000,000,000,000 | 1012 to 1015 (range) |
The additional Hertz incredibly-high frequencies listed below are not likely to be found in use describing electromagnetic radiation such as those discussed in these articles - these are not in common use, but may be used to describe quantum-mechanical wave functions.
Definition of Petahertz PHz |
One petahertz - one followed by 15 zeros, or more formally, One One Petahertz PHZ = 1 x 1015 [cycles per second if we are discussing frequency] |
1015 |
---|---|---|
Definition of Exahertz EHz | One exahertz - one followed by 18 zeros, or One EHZ = 1 x 1018 |
1018 |
Definition of Zetahertz ZHz | One zetahertz -one followed by 21 zeros, or One ZHz = 1 x 1021 |
1021 |
Definition of Yotahertz YHz |
One yotahertz - one followed by 24 zeros, or One YHz = 1 x 1024 |
1024 |
Separately at TABLE of EMR FREQUENCIES we provide a separate listing of the frequency in Hertz of various sources of electromagnetic radiation, ranging from ULF - ultra low frequency sources - through UHF - ultra high frequency electromagnetic radiation sources.
Because the possible effects of electromagnetic fields on humans, other animals, and even materials varies significantly by frequency (and wavelength, distance, and other factors).
I read in [the article above]
“One petahertz = ten followed by 15 zeros”
I Believe it should be :
One petahertz = one followed by 15 zeros
The same mistake is repeated for the definitions of : Exahertz Zetahertz Yotahertz. - Y. [Annon]
Thank you for the question on clarifying how to write the value of various high-frequency measurements such as Petahertz, Exahertz, etc.
The correct formula for one PHz is 1 x 10 to the 15th power
Since 1 x anything is identical to that "anything",
10 to the 1th is 10
10 to the 2d power is 10 x 10 = 100 (1 followed by two zeroes) making you correct
1 x 10 to the 15th is exactly equal to 10 to the 15th which you could write as
1,000,000,000,000,000
or 1 followed by fifteen zeroes - you are quite correct and we have amended our article text to be more accurate.
Albert in the article list below
see EMF ELECTROMAGNETIC FIELDS & HUMAN EXPOSURE
Electromagnetic field strength (measured in gauss) falls off as the square of the distance. There is no one fixed number since you need to know the field strength and distance.
About your earlier question, Milligauss relates to Hertz about as "inches" relates to "pounds" - they are different measurement scales.
We could be measuring the frequency with which we hear our alarm clock beeping (maybe one Hertz or one beep per second) or we could be measuring the frequency with which we see a chicken cross the road at my sister's house in Georgia: about 0.0003 Hertz - or about one chicken per hour.
They don't cross very often and some of them who try it get run over.
We could say that Linda's road-crossing-chicken-rate was observed to be 0.0003 Hertz. I calculated that as 1 chicken crossing observed in one hour, or 1/3600 seconds = 0.0002777
gauss: the centimeter-gram-second unit of magnetic induction, equal to the magnetic induction of a magnetic field in which one abcoulomb of charge, moving with a component of velocity perpendicular to the field and equal to one centimeter per second, is acted on by a force of one dyne;
1 maxwell per square centimeter or 10− 4weber per square meter. Symbol: G. - dictionary.com retrieved 2016/03/29
hertz, the standard unit of frequency in the International System of Units (SI), equal to one cycle per second. Abbreviation: Hz. - op. cit.
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