Scientists Say: Ampere

This is a unit of electric current


How much power is going through these wires? That electric current could be measured in amperes, though usually it is measured in watts.


Ampere (noun, “AM-peer”)

This is a unit of electric current. Start with two infinitely long materials that can conduct electric current. Place them one meter (3.3 feet) apart from each other in space. A force between the two materials would pull them together or push them apart. That attraction or repulsion would produce an electrical force of 0.0000002 newtons (a newton is a unit of force) every meter, every second. That is one ampere.

If this seems kind of arbitrary, it is. An ampere is a base unit. A base unit is one of seven different units of measure that all other units are derived from. These units were selected by scientists as international units that everyone would use. The base unit of length is the meter (3.3 feet) and the base unit of time is the second. In 1908, the International Conference of London agreed that the base unit of current would be the ampere.

In a sentence

An electric eel can deliver a jolt of 0.25 ampere, which is 8.5 times more than the zap of a TASER.

Editors note: This post was updated on 2/13/18 to note that amperes are measurements of electric current, not electric charge.

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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