Ampere hour
| ampere hour | |
|---|---|
 Rechargeable batteries Top: AA battery (2500 mA⋅h) Bottom: AAA battery (1000 mA⋅h) | |
| General information | |
| Unit system | Non-SI metric unit |
| Unit of | Electric charge |
| Symbol | A⋅h |
| Conversions | |
| 1 A⋅h in ... | ... is equal to ... |
| SI units | 3600 C |
| Electrostatic units | 1.079253×1013 statC |
| Electromagnetic units | 360 abC |
| Gaussian units | 1.079253×1013 Fr |
An ampere hour or amp hour (symbol: A⋅h or A h; often also unofficially denoted as Ah) is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3,600 coulombs.[1][2]
The commonly seen milliampere hour (symbol: mA⋅h, mA h, or unofficially mAh) is one-thousandth of an ampere hour (3.6 coulombs).
Use[edit]
The ampere hour is frequently used in measurements of electrochemical systems such as electroplating and for battery capacity where the commonly known nominal voltage is dropped.
A milliampere second (mA⋅s) is a unit of measurement used in X-ray imaging, diagnostic imaging, and radiation therapy. It is equivalent to a millicoulomb. This quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage.[3] The same total dose can be delivered in different time periods depending on the X-ray tube current.
To help express energy, computation over charge values in ampere hour requires precise data of voltage: in a battery system, for example, accurate calculation of the energy delivered requires integration of the power delivered (product of instantaneous voltage and instantaneous current) over the discharge interval.[4] Generally, the battery voltage varies during discharge; an average value or nominal value may be used to approximate the integration of power.[5]
Other measures of electric charge[edit]
The Faraday constant is the charge on one mole of electrons, approximately equal to 26.8 ampere hours. It is also used in electrochemical calculations.
Examples[edit]
- An AA size dry cell has a capacity of about 2000 to 3000 milliampere hours.
- An average smartphone battery usually has between 2500 and 4000 milliampere hours of electric capacity.
- Automotive car batteries vary in capacity but a large automobile propelled by an internal combustion engine would have about a 50-ampere-hour battery capacity.
- Since one ampere hour can produce 0.336 grams of aluminium from molten aluminium chloride, producing a ton of aluminium requires transfer of at least 2.98 million ampere hours.[6]
See also[edit]
References[edit]
- ^ "electric charge (Symbol Q). IEV 113-02-10". electropedia.org. International Electrotechnical Commission (IEC). 2020. Retrieved 2020-09-20.
Note 7 to entry: The coherent SI unit of electric charge is coulomb, C. The unit ampere hour is used for electrolytic devices, such as storage batteries: 1 A·h = 3,6 kC.
- ^ Thompson, Ambler; Taylor, Barry N. (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811 (PDF) (2nd ed.). Gaithersburg: National Institute of Standards and Technology. p. 45.
To convert from ampere hour (A·h) ... to coulomb (C) ... Multiply by 3.6 E+03
- ^ X-ray Safety Handbook, 9.0 Terms and Definitions, VirginiaTech Environmental, Health and Safety Services Archived July 23, 2007, at the Wayback Machine
- ^ Efty Abir, Najrul Islam (2016). "How to Calculate Amp Hours – Learn of Convert Watts to Amps". Leo Evans. Retrieved 8 December 2016.
- ^ National Research Council (U.S.) (2004). Meeting the energy needs of future warriors. National Academies Press. p. 27. ISBN 0-309-09261-2.
- ^ T. L. Brown, H. E. Lemay Jr, "Chemistry the Central Science", Prentice-Hall, 1977 ISBN 0-13-128769-9 page 562
 | This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |