Browse Definitions:
Definition

wave number

The term wave number refers to the number of complete wave cycles of an electromagnetic field (EM field) that exist in one meter (1 m) of linear space. Wave number is expressed in reciprocal meters (m-1).

The wave number for an EM field is equal to 2 pi divided by the wavelength in meters. (In some references, it is defined as the reciprocal of the wavelength in meters; in still others, it is defined as the reciprocal of the wavelength in centimeters.) As the wavelength grows shorter, the wave number becomes larger.

Wave number is usually specified for an EM field in a vacuum, also called free space. In most situations, the air is equivalent to a vacuum. In media other than free space, the wave number for a given EM field may increase. When a ray of light passes from air into water or glass, or a radio signal propagates through a polyethylene dielectric rather than air, the wavelength is shortened because the speed of propagation decreases. This causes the wave number to increase.

In free space, the wave number k (in reciprocal meters) is related to the frequency f (in hertz) according to the following formula:

k = f/c

where c is the speed of EM propagation in free space, approximately equal to 2.99792 x 108 meters per second.

In media other than free space, c must be multiplied by a velocity factor v. The velocity factor for a particular medium is the ratio of the speed of EM propagation in that medium to the speed of EM propagation in free space. As such, the velocity factor is always greater than 0 and less than or equal to 1. Taking velocity factor into account, the above formula becomes:

k = f/(vc)

See also EM field, frequency, and wavelength.

This was last updated in September 2005

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

SearchSecurity

  • Advanced Encryption Standard (AES)

    The Advanced Encryption Standard, or AES, is a symmetric block cipher used by the U.S. government to protect classified ...

  • identity theft

    Identity theft, also known as identity fraud, is a crime in which an imposter obtains key pieces of personally identifiable ...

  • spear phishing

    Spear phishing is an email-spoofing attack that targets a specific organization or individual, seeking unauthorized access to ...

SearchHealthIT

SearchDisasterRecovery

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

  • disaster recovery as a service (DRaaS)

    One approach to a strong disaster recovery plan is DRaaS, where companies offload data replication and restoration ...

SearchStorage

  • ZFS

    ZFS is a local file system and logical volume manager created by Sun Microsystems to control the placement, storage and retrieval...

  • CIFS (Common Internet File System)

    CIFS (Common Internet File System) is a protocol that gained popularity around the year 2000, as vendors worked to establish an ...

  • GlusterFS (Gluster File System)

    GlusterFS (Gluster File System) is an open source distributed file system that can scale out in building-block fashion to store ...

SearchSolidStateStorage

  • Tier 0

    Tier 0 (tier zero) is a level of data storage that is faster, and perhaps more expensive, than any other level in the storage ...

  • PCIe SSD (PCIe solid-state drive)

    A PCIe SSD (PCIe solid-state drive) is a high-speed expansion card that attaches a computer to its peripherals.

  • SSD caching

    SSD caching, also known as flash caching, is the temporary storage of data on NAND flash memory chips in a solid-state drive so ...

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close