Electric Current Flashcards
In a direct current, the direction of the flow of
electric charge does not change, although the current may increase and decrease.
There are two basic types of electric current—
direct current (DC) and alternating current (AC).
Alternating current
regularly reverses direction.
Alternating current’s main advantage is that its
voltage (electrical pressure) can be easily increased or decreased (by devices called transformers).
Direct current, however, is needed by
electronic devices and for such processes as charging storage batteries and electroplating.
An advantage of direct current is
that it can be readily produced by batteries for use in portable devices
Current Electricity is produced by
creating a difference in electric potential between two points connected by a conductor.
A potential difference exists between two points when one has
more electrons than the other. The point with excess electrons is called the negative terminal; the other, the positive terminal.
The potential difference between the positive and negative terminals creates
an electrical pressure called electromotive force (emf), or voltage.
The two most common ways of creating a voltage to produce current are
chemically (using batteries) and by electromagnetic induction (using generators)
One of the most useful properties of electricity is its ability to
produce heat.
Electricity produces heat in a conductor as it overcomes
the conductor’s resistance to the flow of electrons through it, just as mechanical energy produces heat in overcoming friction.
Another very useful property of electricity is that it can be a source of
magnetism; electrons flowing through a wire create a magnetic field around the wire. This effect is the basis for the operation of electromagnets, which make possible electric motors, telephones, loudspeakers, and many other devices.
