Top: AA battery (2500 mA⋅h)
Bottom: AAA battery (1000 mA⋅h)
|Non-SI metric unit|
|1 A⋅h in ...||... is equal to ...|
An ampere hour or amp hour (symbol Ah; also denoted A·h or A h) 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 3600 coulombs. The commonly seen milliampere hour (mAh or mA·h) is one-thousandth of an ampere hour (3.6 coulombs).
A milliampere second (mA·s) is a unit of measure used in X-ray imaging, diagnostic imaging, and radiation therapy. This quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage. The same total dose can be delivered in different time periods depending on the X-ray tube current.
An ampere hour is not a unit of energy. 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. Generally, the battery voltage varies during discharge; an average value or nominal value may be used to approximate the integration of power.
Other measures of electric charge
- An AA size dry cell has a capacity of about 2 to 3 ampere hours.
- 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.
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