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3. Electric Current

It is easy to imagine water flowing through a pipe; depending on the pressure of the source, the water will flow through a pipe with a certain velocity. We can use this as a rough analogy of the flow of electrons through a wire. Here are the differences:

  • Instead of water molecules flowing as a liquid through a pipe, we have electrons moving within a conductor. Wires are made from very conductive metals, which have the property that they have many conduction electrons (free electrons) that are available to move through the material.
  • Instead of pressure or gravity causing water to flow in pipes, flow of electrons in a wire is caused by a voltage difference between two ends of a wire. This creates an electric field that pushes the free electrons through the wire. (Note: the electrons would travel in the opposite direction of the electric field because an electric field will oppose electrons and attract protons).

We would call the resulting flow of electrons through a wire an electric current, and this power can be harnessed by attaching the current to an external load. Wires merely bring a current of flowing electrons to household items to provide a source of power. This requires an external source of current, such as a solar cell.

Fig-17-02.gif

Above: The same current flow of current will result in a different motion of the particle, depending on whether the particle is positively or negatively charged.

Source: whs.wsd.wednet.edu. 1 Jan. 2012. <http://whs.wsd.wednet.edu/faculty/bu...iccurrent.html>