Electric Current

Electric current

An electric current is the flow of electrons around a conductive path (a circuit made of conducting wires).

I like to imagine the current to be like a river carrying water down from a place of higher ground down to the sea.

Electric current is the movement of electrons through a conducting medium (wires). The size of the electric current is measured in Amperes (Amps (A)). These units are named after André-Marie_Ampère.

The size of this quanitity is proportional to the number of electrons (the total charge) passing a point in time.

If we go back to Static electricity we find that the unit of Charge is the Coulomb and in terms of units we find that is 1 Coulomb of charge passes a point in 1 second then a current of 1A is said to have flowed.

Description of electric current as flow of charge 1 A = 1 C s– 1

However this simple definition of an Ampere is not tolarable as far as SI standard units require

because they dont use the coulomb but by its definition from the amp

so here is the official definition of the Ampere

  • The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 x 10–7 newton per metre of length.
  • http://www.bipm.org/en/si/si_brochure/chapter2/2-1/ampere.html

This definition might be better held off until the later chapters, as we discuss and explore forces on current carrying conductors in the electromagnetism section.

Ohms Law


Alternating Circuits

Simple alternating current electric circuits mr Fendt

As useful and as easy to understand as DC is, it is not the only “kind” of electricity in use. Certain sources of electricity (most notably, rotary electro-mechanical generators) naturally produce voltages alternating in polarity, reversing positive and negative over time. Either as a voltage switching polarity or as a current switching direction back and forth, this “kind” of electricity is known as Alternating Current (AC)



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