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Related to frequency: frequency modulation, Sound frequency


see harmonic motionharmonic motion,
regular vibration in which the acceleration of the vibrating object is directly proportional to the displacement of the object from its equilibrium position but oppositely directed.
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; wavewave,
in physics, the transfer of energy by the regular vibration, or oscillatory motion, either of some material medium or by the variation in magnitude of the field vectors of an electromagnetic field (see electromagnetic radiation).
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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.

Frequency (wave motion)

The number of times which sound pressure, electrical intensity, or other quantities specifying a wave vary from their equilibrium value through a complete cycle in unit time. The most common unit of frequency is the hertz (Hz), which is equal to 1 cycle per second. In one cycle there is a positive variation from equilibrium, a return to equilibrium, then a negative variation, and return to equilibrium. This relationship is often described in terms of the sine wave, and the frequency referred to is that of an equivalent sine-wave variation in the parameter under discussion. See Frequency measurement, Sine wave, Wave motion

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.


Symbol: f , ν. The number of oscillations per unit time of a vibrating system. Frequency is measured in hertz. The frequency of a wave is the number of wave crests passing a point per unit time. For light and other electromagnetic radiation, it is related to wavelength λ by ν = c /λ, where c is the speed of light.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



The frequency of an event A is the ratio m/n of the number m of occurrences of A in a given series of trials to the total number n of trials. If the trials are independent and there is a definite probability p of the occurrence of A in an individual trial, then, for arbitrarily small ∊ > 0, at sufficiently large m it is practically certain that the frequency m/n satisfies the inequality


The term “frequency” is used in mathematical statistics to designate the number of elements of a set that have a specified attribute.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The number of cycles completed by a periodic quantity in a unit time.
The number of times an event or item falls into or is expected to fall into a certain class or category.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


The number of oscillations per second (a) of the current or voltage in an alternating-current electric circuit, or (b) of a sound wave, or (c) of a vibrating solid object; expressed in hertz (abbr. Hz) or in cycles per second (abbr. cps).
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


frequencyclick for a larger image
i. The number of recurrences of a periodic phenomenon in a unit of time.
ii. The number of cycles completed in one second. One cycle per second is the basic unit of measurement of frequency and is called a hertz.
iii. The number of services operated by an airline per day or per week over a particular route.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved


1. Physics the number of times that a periodic function or vibration repeats itself in a specified time, often 1 second. It is usually measured in hertz.
2. Ecology
a. the number of individuals of a species within a given area
b. the percentage of quadrats that contains individuals of a species
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


The number of oscillations (vibrations) in one second. Frequency is measured in Hertz (Hz), which is the same as "oscillations per second" or "cycles per second." For example, the alternating current in a wall outlet in the U.S. and Canada is 60Hz. Electromagnetic radiation is measured in kiloHertz (kHz), megahertz (MHz) and gigahertz (GHz). See wavelength, frequency response, audio, carrier and space/time.

The frequency is the number of oscillations per second. The higher the frequency (the closer the ripples would be in this diagram) and the shorter the wavelength.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
The NSS_Slovenia focuses on the relative frequency of the international security and security (research units 1, relative frequency (1)) enabling also: a) the security relational links between security risks and threats (research units 2, relative frequency (2)), national and internal seucirty environment (research units 1, relative frequency 6) and b) the settings of the rule of law (research units 1, relative frequency (4)), development encounters (research units 1, relative frequency (4)), migration and human rights fixings (research units 2, relative frequency (1)), security environment and climate change (research units 3, relative frequency (2)).
In this section, we extract gear fault features in the torsional resonance frequency region, instead of around gear meshing frequency and its harmonics that are usually focused in conventional methods.
Thus, when the original marker allele was distributed in the donor and receptor with a certain frequency, the foreground selection using MBLUP selection had more advantages.
All telecommunications companies except for Vodafone obtained frequencies on the best frequency band of 900 MHz and part on the other frequency band.
All users of frequency spectrum are therefore advised in their own interest to stop using frequency spectrum without a valid license from PTA.
The spacing between frequency spectrum lines in the FFT, or the width of frequency buckets that signal energy is apportioned to, is called the frequency resolution.
Because frequency management is a process, our journey will be made through a series of process improvements.
The software now indicates the spacing between a microphone frequency and its neighbouring frequencies to the 'left' and the 'right', whether this is another carrier or an intermodulation product.
In other words, said Mehta, "spike frequency refers to how fast the spikes come.
Is there a similar relationship between the unemployment rate and medical professional liability claim frequency? To examine this possibility, we first took a look at claim frequency as measured by the National Practitioner Data Bank and compared it to the unemployment rate from 1991 through 2009 (graph 1).
The petition stated that while Liberty was no longer engaged in broadcasting business, "and despite the underutilization or, worse, non-utilization at all of the conditionally assigned said frequencies within the prescribed period, respondent Liberty continued to illegally hoard the said 700 MHz broadcast frequency."
Dakila Carlo Cua said his House Bill 8134 or 'An Act Systematizing Spectrum User Fees Imposed Against Radio Frequency Bands' will penalize telco companies who 'hoard' frequencies.