Definitions of Hertz, Kilohertz, etc.

This article defines and compares frequency measurements expressed in Hertz, Kilohertz kHz, Megahertz MHz, Gigahertz GHz, and Terahertz THz .

Q&A on Definitions of Kilohertz, Megahertz, Gigahertz, Terahertz

These questions & answers about the definitions of the various measures of frequency were posted originally

at DEFINITIONS of HERTZ, KHz MHz GHz THz - we hope you'll review the definitions given there.

On 2023-12-21 by Bill BALHARRY - Why do I sometimes see a capital "K" on KHz instead of kHz

In most cases you quote the Kilohertz abbreviation as kHz, i.e. with a lower case 'k' , however in some Frequency Definitions tables I see the Kilohertz abbreviation as KHz, i.e. with a capital 'K' .

Are both acceptable, or should it really be " kHz " ?

And if it should be with a lower case ' k' , just as you have used lower case for "daHertz" and "hHertz" why, when in all the other definitions you use a capital ?

Reply by InspectApedia Publisher (mod) kHz is correct; electrical engineers are not always careful about capitalization

@Bill BALHARRY,

Most expert sources that we have reviewed abbreviate the term kilohertz as kHz. That is with a lower case k and z and an upper case H.

But it was very interesting to see a capital k used in a number of perfectly scholarly documents and even in some search engine results.

And indeed over the 60 years of writing about this topic and term neither I nor other electrical engineers I worked with have always been meticulously consistent in Kapitalization.

Since it's not ambiguous in this case, that is, we're not mixing up the meaning of k as "thousands" or kilohertz, kHz has thousands of cycles, we're in luck.

Still, we appreciate consistency as much as the next person. And it's always helpful to know what some of our readers might find troublesome or confusing.

You'll notice that a recent web-search found at least one "major" dictionary, Collins, whose entry wrote the frequency using a capital K.

Properly we should write kilohertz as kHz.

Thanks for your thoughtful and polite discussion.

Daniel

How many seconds are between pulses at a 3 mHz setting on a sleep aid device?

if the mefahertz is 3 for sleep, could you tell me how many seconds between each megahertz like a drum.

Or whatever the sleep pattern is Thank you, Connie On 2021-03-16 by connie smith :

Reply by danjoefriedman (mod) - 3 mHz = 1 / 3,000,000 between pulses

@connie smith,

One megahertz - one million cycles per second = 1,000,000

so if you have some device set to 3 Mhz that's 3 million cycles every second -

Which frequency measurement is better?

Is a yotahertz better than a hertz On 2020-12-23by Anonymous -

Reply by danjoefriedman (mod) - neither

Anon

1 yottahertx = 1 septillion hertz

It's not a better nor worse measurement but would be more useful when expressing very large numbers or cycle rates.

How many zeros in a PetaHertz?

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]

Reply:

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.

What's the relationship between Hertz and Milligauss?

Albert Asked: how do Hertz and Milligauss relate to one another when I'm looking at electrical field strength measurement?

Moderato reply:

Albert in the RECOMMENDED ARTICLES

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.

• Milligauss is a measurement of the strength of an electromagnetic field. Gauss is a unit measurement of electromagnetic strength. The use of the word "milli" means we are expressing the field strength in thousandths of one gauss.
  
  A technical definition of gauss from dictionary.com is pretty specific, and I'll give it below.
  
  But in a practical sense, if we have standards of exposure to an electromagnetic field that are expressed in gauss, typically we just want to compare our exposure measurement (or estimate) with the number in the standard.
  
  As long as we keep the units of measurement the same, gauss, we can make comparisons.
• Hertz measures cycles per second - one Hertz is one cycle per second.
  
  Unlike gauss that is a measurement unit for the strenght of a specific thing (an electromagnetic field), hertz is a generic frequency measurement.

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

Formal definition of gauss

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

Formal definition of hertz

hertz, the standard unit of frequency in the International System of Units (SI), equal to one cycle per second. Abbreviation: Hz. - op. cit.

Can a wavelength of one lightsecond actually be produced

As it is 1 lightsecond long I wondered if it is possable to produce it in the first place. On 2018-09-24 by Larry

Clarification by (mod) -

Larry

Just to clear up what I think maybe a misunderstanding about Hertz,

1 hertz frequency means one cycle per second. That's extremely slow, not extremely fast as you were suggesting.

by Larry

I was speaking of wavelenth.

A lightsecond is about 300000000 meters.

by (mod) - A lightsecond is about 300000000 meters.

Thank you for clarifying. I appreciate it. Indeed one light second 300000000 m is almost exactly 1 hz.

That's a very long wavelength and that's a very low frequency.

Can we detect radiowaves at less than 1 hz?

Can we detect radiowaves at less than 1 hz? On 2018-09-23 by Larry

Answer by (mod) - Yes, electromagnetic waves at all of these frequencies can be detected.

Using the right equipment electromagnetic waves at all of these frequencies can be detected.

Explain why we see lightning before we hear the thunder

Please answer the question I searched for above:

We see lightning before we hear thunder. I understood this is because light and sound, both electromagnetic waves, don't travel at the same speed. On 2018-06-08 by Andrew -

Explanation by (mod) - what is the speed of light compared with the speed of sound?

Right, Andrew.

Light travels at about 983,571,056 feet per second or about 299 792 458 m / s or about 186,282 miles per second.

Sound travels at about 1125 feet per second, or about 343 m / s in dry air at 20 degC.

When a lightning bolt flashes within visual range, the light reaches you 874,285 times faster than the sound waves.

It's fine to consider light in the electromagnetic spectrum. Light is perceived by photos arriving at the retina of the eye and being transformed into signals sent to the visual cortex area of the brain.

Sound is perceived by the movement of air (not photos or light energy), impacting on the ear drum and then being converted to signals sent to the auditory cortex is the part of the temporal lobe of the brain.

Light can and does travel through a vacuum as well as through air or the atmosphere.

In a vacuum (the complete absence of air, for example) no sound would be transmitted.

In sum, when comparing light and sound, the transmission media are different, the mechanism of perception is different, and their speeds are vastly different.

If decibel measure the volume/intensity of sound what does hertz measure?

Greetings. I need practical approach to this. If decibel measure the volume/intensity of sound what does hertz measure?

I know it's oscillation per second but in an an unscientific language, what does it measure?

Is it distance covered or type of sound or what? Use examples if possible.
Hope to hear from you guys soon. On 2017-09-25 by OBI DANIEL

Answer by (mod) - Herz measures frequency of occurrence; relationship between decibels and frequency?

Herz measures frequency in cycles per second. And more generally, Herz measures frequency of occurrence of anything of interest that occurs at regular intervals or cycles.

Decibels, as you say, measure the intensity of sound (on a logarithmic scale, meaning that if you double the decibel reading you are multiplying its intensity by a factor of 10).

There is a relationship between hertz and sound frequency - a human can hear at best sound waves in the frequency range of about 20 hz to 20khz or 20 thousand cycles per second.

Some animals can hear higher frequencies than we do and others (whales) lower frequencies.

The Hertz measurement in cycles per second is not, however restricted to sound waves.

It can measure any frequency of anything. If I wave my hand out the window ten times a second, that event is occurring at 10 herz.

What is the formula of 1 hertz ?

What is the formula of 1 hertz On 2016-10-23 by Roshan Kumar

Expalanation by (mod) - definition of 1-hertz = one cycle per second

Roshan

1 Hertz means that whatever you're measuring, it cycles ONE time per second.

Are pentaherz frequencies achievable?

Can you tell me if pentaherz frequencies are actually achievable? On 2015-06-04 by Mihai

Answer by (mod) - yes

Mihai,

Yes there is research discussing signals (and antannae) in the pentahertz (perhaps you meant petahertz) frequency range as well as exahertz. See

Sharma, Krishna Hari, Abhishek Kandwal, and Sunil Kumar Khah. "A novel nano-antenna design for pentahertz frequency." In PROCEEDING OF INTERNATIONAL CONFERENCE ON RECENT TRENDS IN APPLIED PHYSICS AND MATERIAL SCIENCE: RAM 2013, vol. 1536, no. 1, pp. 1151-1152. AIP Publishing, 2013.

Ismail, M. K. H., and M. Esa. "Preliminary design of rectangular nano-antenna at PHz." In Applied Electromagnetics (APACE), 2010 IEEE Asia-Pacific Conference on, pp. 1-4. IEEE, 2010.

Haynes, Kate. "Magneto-optical spectroscopic studies of multi-heme enzymes." PhD diss., University of East Anglia, 2013.

Petahertz

Süßmann, Frederik, and Matthias F. Kling. "Attosecond measurement of petahertz plasmonic near-fields." In SPIE NanoScience+ Engineering, pp. 80961C-80961C. International Society for Optics and Photonics, 2011.

Weiner, J., and Frederico D. Nunes. "High-frequency response of subwavelength-structured metals in the petahertz domain." Optics express 16, no. 26 (2008): 21256-21270.

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