Scientists Say: Ampere | Science News for Students

Scientists Say: Ampere

This is a unit of electric current
Feb 12, 2018 — 6:30 am EST
electric grid

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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Power Words

(more about Power Words)

ampere     A rate of electrical current equal to one coulomb per second.

conductor     (in physics and engineering) A material through which an electrical current can flow.

current     A fluid — such as of water or air — that moves in a recognizable direction. (in electricity) The flow of electricity or the amount of charge moving through some material over a particular period of time.

eel     A fish with a snake-like body and no scales. Many migrate from freshwater to salt water when it’s time to spawn.

electric charge     The physical property responsible for electric force; it can be negative or positive.

electric current     A flow of electric charge — electricity — usually from the movement of negatively charged particles, called electrons.

force     Some outside influence that can change the motion of a body, hold bodies close to one another, or produce motion or stress in a stationary body.

newton     A unit of force named for Sir Isaac Newton, a 17th century English physicist and mathematician. One newton is an amount that would give a mass of one kilogram an acceleration of one meter per second per second.

TASER     A brand-name of version of a “conducted electrical weapon” used by police, the military, prisons, security guards and others. It sends out electrodes that deliver a stunning discharge of electricity into a person to incapacitate them. Such devices are popularly referred to as stun guns.