# Intro

Amperage describes the quantity of charge carriers that are being moved passed a point in any given second.

One of the simplest (though not actually the official) definitions of an ampere (amp) is 1 *coulomb* of charge carriers passing through a given location per second.

One coulomb is equal to 6.242 x 10^18 (6,242,000,000,000,000,000) charge carriers. A fantastically large number, but given the relative size of electrons, one can imagine that number of charges moving on a relatively modest wire. Consider household wiring, which is typically 14 or 12 gauge, and rated at carrying 10 or 15 amps (at 120 volts), respectively.

## Common Amperages

Appliance | Amperage |
---|---|

60 Watt incandescent light bulb | 500mA (0.5A) |

10 Watt LED (60 Watt incandescent equivalent) | ~100mA (0.1A) |

Hair Dryer | 12 amps |

## Amp Hours (Ah)

When describing the quantity of charge either available, or used, *amp hours* (Ah) are used. An amp hour is an hour’s worth of amps, or 3,600 coulombs (since there are 3,600 seconds in an hour).

Amp hours are often expressed in *milliampere hours* (mAh), which is one-thousandth of an amp hour, or 3.6 coulombs. For reference, a typical AA NiMH rechargeable battery will have ~2500 mAh (2.5Ah), and a D NiMH rechargeable has ~10,000 mAh (10 Ah).

## Common Unit Magnitudes

Magnitude | Value in amps |
---|---|

nanoamp (nA) | 0.000000001A |

microamp (µA) | 0.000001A |

milliamp (mA) | 0.001A |

amp (A) | 1.0A |

# Further Reading

For a much more in depth discussion regarding amps, see Part 2 of the Electronics Tutorial