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In physics, frequency refers to the number of waves passing through a certain point in one unit of time. It also translates to vibrations or cycles an object produces in unit time when moving periodically. The SI unit to measure frequency is hertz (Hz), with one hertz referring to one cycle a body completes in a second. When 1,000Hz combine, it becomes the frequency kilohertz (kHz). 

Whether you’re a physics freak or want to understand the frequency kilohertz (kHz), you must know its exact definition and meaning. There are many bigger units for frequency, such as megahertz (MHz), gigahertz (GHz), and terahertz (THz). 

So, how much kHz makes MHz, GHz, and THz? Let’s find the answers along with a detailed definition of frequency in physics and the kHz’s application in different fields. 

What is Frequency in Physics?

It is important to understand the correct frequency definition in physics before understanding its measurement unit: the kilohertz (kHz).

When a body is in periodic motion, it completes one cycle or vibration after experiencing consecutive events and returning to its starting position. For simple harmonic motion, frequency denotes the number of oscillations or cycles produced in one unit of time (seconds, minutes, or hours).

The three most common symbols for frequency are “f,” “nu (ν)” (in Greek), and omega “(ω).” Nu is used when describing electromagnetic waves like gamma rays, light, and X-rays. Meanwhile, omega specifies angular frequency, or the number of times an object revolves or rotates in radians each unit of time. There is also another type of frequency called temporal frequency, referring to the number of occurrences of an object’s repeating event in one unit of time.

Rotational frequency refers to revolution per minute (r/min), or RPM. One hertz equals 60 RPM, meaning one frequency kilohertz (kHz) will be 60,000 RPM.

The frequency indirectly depends on the time interval or period (T), meaning f is the reciprocal of T. Thus, the formula of frequency is as follows:

f = 1/T


  • f = frequency
  • T = time (in seconds)

If an object takes one cycle or vibration in 1 second, its frequency will be:

f = 1/1

f = 1 per sec

But if the time is ½ second for one cycle, the frequency will be:

f = 1/1½ 

f = 2 per sec

If the time is 1/100 an hour, the frequency is as follows:

f = 1/ 1/100

f = 100 per hr

The SI unit used to specify frequency is the hertz (Hz), named after Heinrich Rudolf Hertz, a 19th-century German physicist. 

Is Frequency and Wavelength the Same Thing?

Many people confuse frequency and wavelength since both measure waves. However, they have significant differences, especially in their definition and meaning.

Frequency measures the total number of oscillations produced in a unit of time, while the wavelength is a wave’s overall length.

Moreover, frequency’s formula includes the time, meaning the total number of cycles an object completes in a specific unit of time. On the other hand, the wavelength is concerned with distance instead of time. 

Another difference between both is the measuring unit. Frequency uses hertz (Hz) as its measuring unit, while the wavelength’s SI unit is the meter. You may have also heard about the frequency kilohertz (kHz).

The fourth distinction is their equations. While frequency includes the ratio between wavelength and speed, the wavelength is the ratio of frequency and speed. This means they’re somehow related when studying waves.

Both terms come from the below formula:

Speed = Frequency x Wavelength

C = f × λ

This means:

Wavelength = Speed of the wave / Frequency of the wave


Frequency = Speed of the wave / Wavelength of the wave

f = cλ


  • λ = wavelength in meters
  • C = speed of the wave in m/s
  • f = frequency in hertz

The audible sound waves usually have a frequency of 20kHz. Meanwhile, visible light has a wavelength of 400 to 700 nm.

What is Hertz (Hz)?

Hertz is the SI unit to specify the frequency of one cycle per second (CPS). In simpler words, Hz measures the change in the state of a wave, current, or other waveforms.

However, the SI unit of frequency is different in spectroscopy—the wavenumber—which measures the number of waves formed in one unit of distance. 

CPS was used to measure the frequency earlier, but Heinrich Hertz coined “hertz” in 1930. The Conférence générale des poids et mesures (CGPM) adopted it in 1960, officially replacing CPS. 

What is Frequency Kilohertz (kHz)?

Kilohertz, or kHz, measures frequency the same way as hertz, but its one unit refers to 1,000 Hz. kHz measures higher frequencies, such as those in alternating current, wireless signals, and audio signals. 

A frequency kilohertz (kHz) may also be referred to as megahertz (MHz), gigahertz (GHz), or terahertz (THz). You may have seen this unit being used in different fields, such as measuring sound, radio broadcasts, electrical supply, and central processing units (CPU). 

For instance, a radio station with a frequency of 700 kHz means that its transmitter vibrates at 700,000 cycles per second. Some radio stations also operate at a greater frequency range, which is measured in megahertz (MHz), meaning “millions of cycles per second.” 

An FM radio band runs between 88 to 108 MHz, while shortwave radio operates from 5.9 to 26.1 MHz. The tiny baby monitors in your home also work at a higher frequency range, i.e., 49 MHz. Moreover, garage-door openers operate at 40 MHz.

Some other examples include the moon completing more than 12 cycles every year to revolve around Earth. Also, a violin’s A string takes 440 cycles or vibrations per second. 

One kilohertz (kHz) is equivalent to 1,000 hertz (Hz).


Applications of Frequency Kilohertz (kHz)

The standard electrical supply in a U.S. household is 60Hz or 0.06 kHz. This means that the current fluctuates its polarity’s direction with 60 CPS. The line frequency in Europe is 50Hz or 0.05 kHz. When measuring the frequency of broadcast transmissions, kHz or MHz is used since the values are significantly higher. 

Frequency kilohertz (kHz) also measures the intensity of a sound or a human’s hearing capability. For instance, a human can hear a sound with a frequency ranging between 0 to 20 kHz. This range may vary based on age and how intensely a sound is being played.

Kilohertz holds a significant value in measuring the pitch of the piano’s sound. It is also used to express an audio equalizer’s each band. A piano’s middle C has a pitch of 0.263 kHz, but you can boost it by increasing other frequencies to 0.263 kHz along with the equalizer.

In the olden days, you might have seen kHz measuring speeds of CPUs (central processing units). For example, the Intel 4004, the first-ever processor, worked at 740 kHz. Over the years, more processors, such as the Intel Pentium processor, were manufactured. These were designed to operate at MHz. It worked at 60 to 300 MHz of speed. Today, processors work at GHz.

To measure a processor’s speed, we must look at its frequency speed. The higher the number, the quicker it can operate. 

Frequency Kilohertz (kHz) Conversions

Frequency kilohertz can be converted into many units, depending on how big or small the number is. The smallest is Hz, which goes as high as THz. 

Remember, you can’t use every form of hertz for any frequency or speed. Instead, opt for the higher form when dealing with higher frequencies to simplify the measurements. So, here is how converting kHz into different frequency forms looks:

kHz to Hz

One kHz consists of 1,000 Hz. So, multiply the frequency f in Hz by 1,000 to get frequency f in kHz. For example, 5 kHz Hz equals 5,000 Hz. Here is how:

f = 5 x 1000 = 5,000 Hz

kHz to MHz

One kHz equals 0.001 MHz. Thus, divide the frequency f in kHz by 1,000 to yield frequency f in kHz. For instance, 5 kHz means 0.005 MHz. Here is how:

f = 5 / 1000 = 0.005 MHz

kHz to GHz

One kHz means 0.000001 GHz. You must divide the frequency f in kHz by 1,000,000 to get the frequency f in GHz. For example, 5 kHz translates to 0.000005 GHz. The calculation goes as follows:

f = 5 / 1,000,000 = 0.000005 GHz

kHz to THz

One kHz equals 1e-9 THz, so you’ll have to divide the frequency f in kHz by 1,000,000,000 to get the frequency f in THz. For instance, 5 kHz gives 5e-9. 

f = 5 / 1,000,000,000 = 5e-9 THz

Kilohertz (kHz) Summarized

Frequency measures how many times an object completes a cycle or vibrates in periodic motion in one unit of time. It also calculates the number of waves moving at a fixed point in a unit of time (seconds, minutes, or hours). Earlier, “cycles per second” (CPS) was the official unit to measure frequency, which then changed to hertz (Hz) in 1960. 

A kilohertz (kHz) refers to 1,000Hz. It measures higher frequency levels, such as computer processors, sound, and hearing limits. It also calculates radio, audio, and wireless signals and broadcast transmissions. 

One kHz translates to 0.001 MHz, 0.000005 GHz, and 5e-9 THz. Hopefully, our mentioned examples, applications, and conversions helped you understand the frequency kilohertz (kHz)!

What is the Definition and Meaning of the Frequency Kilohertz (kHz)? FAQs (Frequently Asked Questions) 

What is the meaning of Hz and kHz?

Hertz (Hz) is the frequency or number of cycles an object completes in a second. Kilohertz (kHz) refers to the number of thousand cycles happening every second. There is no significant difference between terms since you can easily interconvert them. However, hertz is the SI unit of frequency, and kHz, MHz, GHz, and THz are just its different forms. All of them specify frequency.

What does kHz measure?

A kilohertz (kHz) measures the frequency or how many thousand cycles occurred in a unit of time or second. While hertz calculates cycles per second, kHz refers to one thousand cycles in the same time unit. This means 5 kHz means 5,000 CPS, or cycles per second. kHz mainly measures higher frequencies, such as audio signal processing and radio frequencies.

What is the unit of frequency?

Hertz (Hz) is the SI unit of frequency, which equals one cycle completed per second. Heinrich Hertz coined it in 1930. Thirty years later, the Conférence générale des poids et mesures (CGPM) officially accepted it to replace CPS in 1960.

What does kHz mean in sound?

kHz means 1,000 cycles completed in one second. In sound, it means “samples per second.” Your audio CDs will have a 44.1 kHz frequency, meaning its analog signal is sampled 44,100 times each second.

What is the frequency of a wave?

The frequency of a wave is the number of waves passing through a specific point at a certain time. If a wave takes ½ second to pass, its frequency will be 2 per second. Similarly, if the wave consumes 1/100 in an hour, the frequency will be 100 an hour. Remember, frequency is not the same as wavelength.

What is the difference between wavelength and frequency?

Frequency and wavelength are interlinked but have different meanings. While frequency refers to the ratio of wavelength and speed relative to speed, wavelength is the ratio between frequency and speed. Frequency is measured in hertz (Hz), and wavelength is calculated in meters (m). An audible sound ranges at 20kHz. Comparatively, visible light has a wavelength between 400 to 700 nm.

What is the symbol of hertz?

Hertz is the SI unit of frequency with “Hz” as its symbol.

What kHz is a human voice?

Assuming the voice to be natural and soft, a human voice can have a frequency range of 2 kHz to 4 kHz when someone is standing at a distance of 1 meter in front of that person. This is the normal talking frequency range of humans.

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