Tesla (unit)

The tesla (symbol T) is a derived unit of the magnetic induction (also, magnetic flux density) in the International System of Units.

One tesla is equal to one weber per square metre. The unit was announced during the General Conference on Weights and Measures in 1960 and is named[1] in honour of Nikola Tesla, upon the proposal of the Slovenian electrical engineer France Avčin.

The strongest fields encountered from permanent magnets on Earth are from Halbach spheres and can be over 4.5 T. The record for the highest sustained pulsed magnetic field has been produced by scientists at the Los Alamos National Laboratory campus of the National High Magnetic Field Laboratory, the world's first 100-tesla non-destructive magnetic field.[2] In September 2018 researchers at the University of Tokyo generated a field of 1200 T which lasted in the order of 100 microseconds using the electromagnetic flux-compression technique.[3]

Tesla
Unit systemSI derived unit
Unit ofMagnetic flux density
SymbolT 
Named afterNikola Tesla
In SI base units:kgs−2A−1

Definition

A particle, carrying a charge of one coulomb, and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second, experiences a force with magnitude one newton, according to the Lorentz force law. As an SI derived unit, the tesla can also be expressed as

(The last equivalent is in SI base units).[4]

Units used:

A = ampere
C = coulomb
kg = kilogram
m = metre
N = newton
s = second
H = henry
V = volt
J = joule
Wb = weber

Electric vs. magnetic field

In the production of the Lorentz force, the difference between electric fields and magnetic fields is that a force from a magnetic field on a charged particle is generally due to the charged particle's movement,[5] while the force imparted by an electric field on a charged particle is not due to the charged particle's movement. This may be appreciated by looking at the units for each. The unit of electric field in the MKS system of units is newtons per coulomb, N/C, while the magnetic field (in teslas) can be written as N/(C·m/s). The dividing factor between the two types of field is metres per second (m/s), which is velocity. This relationship immediately highlights the fact that whether a static electromagnetic field is seen as purely magnetic, or purely electric, or some combination of these, is dependent upon one's reference frame (that is, one's velocity relative to the field).[6][7]

In ferromagnets, the movement creating the magnetic field is the electron spin[8] (and to a lesser extent electron orbital angular momentum). In a current-carrying wire (electromagnets) the movement is due to electrons moving through the wire (whether the wire is straight or circular).

Conversions

One tesla is equivalent to:[9]

10,000 (or 104) G (Gauss), used in the CGS system. Thus, 10 kG = 1 T (tesla), and 1 G = 10−4 T = 100 µT (microtesla).
1,000,000,000 (or 109) γ (gamma), used in geophysics.[10] Thus, 1 γ = 1 nT (nanotesla).
42.6 MHz of the 1H nucleus frequency, in NMR. Thus, the magnetic field associated with NMR at 1 GHz is 23.5 T.

One tesla is equal to 1 V·s/m2. This can be shown by starting with the speed of light in vacuum,[11] c = (ε0μ0)−1/2, and inserting the SI values and units for c (2.998×108 m/s), the vacuum permittivity ε0 (8.85×10−12 A·s/(V·m)), and the vacuum permeability μ0 (12.566×10−7 T·m/A). Cancellation of numbers and units then produces this relation.

For the relation to the units of the magnetising field (ampere per metre or Oersted), see the article on permeability.

Examples

  • 31.869 µT (3.2 × 10−5 T) – strength of Earth's magnetic field at 0° latitude, 0° longitude
  • 5 mT – the strength of a typical refrigerator magnet
  • 0.3 T – the strength of solar sunspots
  • 1.25 T – magnetic flux density at the surface of a neodymium magnet
  • 1 T to 2.4 T – coil gap of a typical loudspeaker magnet
  • 1.5 T to 3 T – strength of medical magnetic resonance imaging systems in practice, experimentally up to 17 T[12]
  • 4 T – strength of the superconducting magnet built around the CMS detector at CERN[13]
  • 8 T – the strength of LHC magnets
  • 11.75 T – the strength of INUMAC magnets, largest MRI scanner[14]
  • 13 T – strength of the superconducting ITER magnet system[15]
  • 16 T – magnetic field strength required to levitate a frog[16] (by diamagnetic levitation of the water in its body tissues) according to the 2000 Ig Nobel Prize in Physics[17]
  • 17.6 T – strongest field trapped in a superconductor in a lab as of July 2014[18]
  • 27 T – maximal field strengths of superconducting electromagnets at cryogenic temperatures
  • 35.4 T – the current (2009) world record for a superconducting electromagnet in a background magnetic field [19]
  • 45 T – the current (2015) world record for continuous field magnets [19]
  • 100 T – approximate magnetic field strength of a typical White dwarf star
  • 108 – 1011 T (100 MT – 100 GT) – magnetic strength range of magnetar neutron stars

Notes and references

  1. ^ "Details of SI units". sizes.com. 2011-07-01. Retrieved 2011-10-04.
  2. ^ "Strongest non-destructive magnetic field: world record set at 100-tesla level". Los Alamos National Laboratory. Retrieved 6 November 2014.
  3. ^ D. Nakamura, A. Ikeda, H. Sawabe, Y. H. Matsuda, and S. Takeyama (2018), Magnetic field milestone
  4. ^ The International System of Units (SI), 8th edition, BIPM, eds. (2006), ISBN 92-822-2213-6, Table 3. Coherent derived units in the SI with special names and symbols Archived 2007-06-18 at the Wayback Machine
  5. ^ Gregory, Frederick (2003). History of Science 1700 to Present. The Teaching Company.
  6. ^ Parker, Eugene (2007). Conversations on electric and magnetic fields in the cosmos. Princeton University press. p. 65. ISBN 978-0691128412.
  7. ^ Kurt, Oughstun (2006). Electromagnetic and optical pulse propagation. Springer. p. 81. ISBN 9780387345994.
  8. ^ Herman, Stephen (2003). Delmar's standard textbook of electricity. Delmar Publishers. p. 97. ISBN 978-1401825652.
  9. ^ McGraw Hill Encyclopaedia of Physics (2nd Edition), C.B. Parker, 1994, ISBN 0-07-051400-3
  10. ^ "Geomagnetism Frequently Asked Questions". National Geophysical Data Center. Retrieved 21 October 2013.
  11. ^ Panofsky, W. K. H.; Phillips, M. (1962). Classical Electricity and Magnetism. Addison-Wesley. p. 182. ISBN 978-0-201-05702-7.
  12. ^ "Ultra-High Field". Bruker BioSpin. Retrieved 2011-10-04.
  13. ^ "Superconducting Magnet in CMS". Retrieved 9 February 2013.
  14. ^ "ISEULT - INUMAC". Retrieved 17 February 2014.
  15. ^ "ITER – the way to new energy". Retrieved 2012-04-19.
  16. ^ "Of Flying Frogs and Levitrons" by M. V. Berry and A. K. Geim, European Journal of Physics, v. 18, 1997, p. 307–13" (PDF). Retrieved 12 May 2013.
  17. ^ "The 2000 Ig Nobel Prize Winners". Retrieved 12 May 2013.)
  18. ^ "Superconductor Traps The Strongest Magnetic Field Yet". Retrieved 2 July 2014.
  19. ^ a b "Mag Lab World Records". Media Center. National High Magnetic Field Laboratory, USA. 2008. Retrieved 2015-10-24.

External links

Belgrade

Belgrade ( BEL-grayd; Serbian: Beograd / Београд, meaning 'white city', Serbian pronunciation: [beǒɡrad] (listen); names in other languages) is the capital and largest city of Serbia. It is located at the confluence of the Sava and Danube rivers, where the Pannonian Plain meets the Balkans. The urban area of the City of Belgrade has a population of 1.23 million, while nearly 1.7 million people live within its administrative limits.One of the most important prehistoric cultures of Europe, the Vinča culture, evolved within the Belgrade area in the 6th millennium BC. In antiquity, Thraco–Dacians inhabited the region, and after 279 BC, Celts conquered the city, naming it Singidūn. It was conquered by the Romans during the reign of Augustus, and awarded city rights in the mid-2nd century. It was settled by the Slavs in the 520s, and changed hands several times between the Byzantine Empire, the Frankish Empire, the Bulgarian Empire and the Kingdom of Hungary before it became the seat of the Serbian king Stephen Dragutin (ruled 1282–1316). In 1521, Belgrade was conquered by the Ottoman Empire and became the seat of the Sanjak of Smederevo. It frequently passed from Ottoman to Habsburg rule, which saw the destruction of most of the city during the Austro-Ottoman wars. Belgrade was again named the capital of Serbia in 1841. Northern Belgrade remained the southernmost Habsburg post until 1918, when the city was reunited. As a strategic location, the city was battled over in 115 wars and razed 44 times. Belgrade was the capital of Yugoslavia from its creation in 1918 to its dissolution in 2006.

Belgrade has a special administrative status within Serbia and it is one of the five statistical regions of Serbia. Its metropolitan territory is divided into 17 municipalities, each with its own local council. The city of Belgrade covers 3.6% of Serbia's territory, and around 24% of the country's population lives within its administrative limits. It is classified as a Beta-Global City.

Glossary of electrical and electronics engineering

Most of the terms listed in Wikipedia glossaries are already defined and explained within Wikipedia itself. However, glossaries like this one are useful for looking up, comparing and reviewing large numbers of terms together. You can help enhance this page by adding new terms or writing definitions for existing ones.

This glossary of electrical and electronics engineering pertains specifically to electrical and electronics engineering. For a broad overview of engineering, see glossary of engineering.

Index of electrical engineering articles

This is an alphabetical list of articles pertaining specifically to electrical and electronics engineering. For a thematic list, please see List of electrical engineering topics. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.

Index of physics articles (T)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

Inductively coupled plasma atomic emission spectroscopy

Inductively coupled plasma atomic emission spectroscopy (ICP-AES), also referred to as inductively coupled plasma optical emission spectrometry (ICP-OES), is an analytical technique used for the detection of chemical elements. It is a type of emission spectroscopy that uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element. It is a flame technique with a flame temperature in a range from 6000 to 10,000 K. The intensity of this emission is indicative of the concentration of the element within the sample.

List of scientists whose names are used as SI units

List of scientists whose names are used as SI units is the list of those scientists whose names are assigned as the names of the international units by the International Committee for Weights and Measures. The International System of Units (abbreviated SI from French: Système international d'unités) is the most widely used system of units of measurement. There are seven base units and 22 derived units (excluding compound units). These units are used both in science and in commerce. Two of the base units and 17 of the derived units are named after scientists. By this convention, their names are immortalised. Below is the list of the scientists whose names are used as SI units. As a rule, the units are written in lowercase letters, but symbols of units derived from the name of a person begin with a capital letter.

List of things named after Nikola Tesla

This article is a list of things named after Nikola Tesla, an influential physicist, engineer and inventor.

Transfer (computing)

In computer technology, transfers per second and its more common secondary terms gigatransfers per second (abbreviated as GT/s) and megatransfers per second (MT/s) are informal language that refer to the number of operations transferring data that occur in each second in some given data-transfer channel. It is also known as sample rate, i.e. the number of data samples captured per second, each sample normally occurring at the clock edge. The terms are neutral with respect to the method of physically accomplishing each such data-transfer operation; nevertheless, they are most commonly used in the context of transmission of digital data. 1 MT/s is 106 or one million transfers per second; similarly, 1 GT/s means 109, or equivalently in the US/short scale, one billion transfers per second.

The choice of the symbol T for transfer conflicts with the International System of Units, in which T stands for the tesla unit of magnetic flux density. "Megatesla per second" would be a reasonable unit to describe the rate of a rapidly changing magnetic field, such as in a pulsed field magnet or kicker magnet, although the equivalent units of "tesla per microsecond" (T/μs) would reflect typical engineering values better.

These terms alone do not specify the bit rate at which binary data is being transferred, because they do not specify the number of bits transferred in each transfer operation (known as the channel width or word length). In order to calculate the data transmission rate, one must multiply the transfer rate by the information channel width. For example, a data bus eight-bytes wide (64 bits) by definition transfers eight bytes in each transfer operation; at a transfer rate of 1 GT/s, the data rate would be 8 × 109 B/s, i.e. 8 GB/s, or approximately 7.45 GiB/s. The bit rate for this example is 64 Gbit/s (8 × 8 × 109 bit/s).

The formula for a data transfer rate is: Channel width (bits/transfer) × transfers/second = bits/second.

Expanding the width of a channel, for example that between a CPU and a northbridge, increases data throughput without requiring an increase in the channel's operating frequency (measured in transfers per second). This is analogous to increasing throughput by increasing bandwidth but leaving latency unchanged.

The units usually refer to the "effective" number of transfers, or transfers perceived from "outside" of a system or component, as opposed to the internal speed or rate of the clock of the system. One example is a computer bus running at double data rate where data is transferred on both the rising and falling edge of the clock signal. If its internal clock runs at 100 MHz, then the effective rate is 200 MT/s, because there are 100 million rising edges per second and 100 million falling edges per second of a clock signal running at 100 MHz.

SCSI (Small Computer Systems Interface) falls in the megatransfer range of data transfer rate, while newer bus architectures like the front side bus, Quick Path Interconnect, PCI Express and HyperTransport operate at the rate of a few GT/s.

Base units
Derived units
with special names
Other accepted units
See also

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