Definition of ampere in US English:


(also A)


  • A unit of electric current equal to a flow of one coulomb per second.

    The SI base unit of electric current, 1 ampere is precisely defined as that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in a vacuum, would produce between these conductors a force of 2 × 10⁷ newton per meter

    • ‘Just as an ampere is a unit of electric current, a magneton is a unit of magnetic dipole moment.’
    • ‘You can calculate the number of watts required by any given device by multiplying the usual voltage times the number of amperes the appliance draws.’
    • ‘The more copper and iron in the alternator, the less heat is generated, and more kilovolt amperes are capable of being produced.’
    • ‘A supply's capacity to provide 12V power is measured in amperes, or amps.’
    • ‘Now we've a problem in our experiment and that is, we have these large magnets which require 14,000 amperes of current at 1000 volts, which we get off the mains and we run it full bore.’
    • ‘The energising coils, through which several hundred amperes of current flows, remains at minus 269 degrees centigrade with the help of about 300 litres of liquid helium in a special vessel called cryostat.’
    • ‘Welding current can reach several thousand amperes at short circuit.’
    • ‘Just a couple hundred amperes of electricity makes it hot,’ he says.’
    • ‘Low conductivity usually indicates a small current flow, but when the total conductivity is calculated over the whole Earth's surface the atmospheric conductivity is quite large, and an appreciable current of about 2000 amperes flows.’
    • ‘There is a procedure to do that with minor power lines - that is, those of less than 100 megavolt amperes and 110 kilovolts.’
    • ‘At its core are four electronic high-performance loads, each of which can handle a maximum current of 50 amperes.’
    • ‘Why should I worry about how many amperes of electricity it takes to run an appliance?’
    • ‘The #16 gauge wire is rated to carry 13 amperes, as compared to the formerly-used # 18 gauge cords that were rated for 10 amperes.’
    • ‘If it has one or more fuses rated above 20 amperes, someone may have tried to avoid power outages by substituting higher amperage fuses.’
    • ‘The amount of power used is only a few micro amperes, but the frequency of the current can vary from 5 to 2,000 Hz.’
    • ‘As a result, they may be rated for 15 amperes, but they may trip at 8 or 10 amperes, because of their design, but if a circuit breaker trips at a server farm, the whole farm could go down.’
    • ‘As the need to backup mission critical kilowatts grows, the amperes also grow.’
    • ‘The tether exploited about 1 ampere at 3500 volts of electricity.’
    • ‘For any object conducting electricity, one can define the resistance in ohms as the ratio of the electrical potential difference applied to the object to current passing through it in amperes.’
    • ‘Where the conventional gyro consumes a substantial amount of electrical power the GPS compass operates from the boat's 12 volt DC bus drawing less than 2 amperes.’


Late 19th century: named after A-M Ampere (see Ampère, André-Marie).