What is CURRENT?
The flow of free electrons in the same general direction from atom to atom is referred to as current and it is measured in amperes (“amps” or “A”). The number of electrons that flow through a conductor’s cross-section in one second determines amps. Current can be expressed in a number of different ways, such as:
Quantity Symbol Decimal
1 milliampere 1 mA 1/1000 A
1 ampere 1 A or 1 amp 1 ampere
1 kiloampere 1 kA 1000 amperes
1 ampere 1 A or 1 amp 1 ampere
1 kiloampere 1 kA 1000 amperes
When discussing current, the direction of current flow needs to be considered. There are two different theories about this: · Conventional Flow · Electron Flow
Conventional Flow: This theory states that electrons flow from positive to negative. Benjamin Franklin theorized this when very little was known about electricity. It states that an invisible fluid known as electricity tended to flow through a wire from the positive to the negative. Ben’s theory became the convention (hence the term “conventional current”) in electrical theory, mathematics, textbooks and electrical equipment for the next hundred years.
Electron Flow: This theory states that electrons flow from negative to positive. When more was known about the behavior of electrons, scientists discovered that electrons actually flow from negative to positive. Since electrons are negatively charged, it follows that they are attracted by positively charged bodies and repelled by negatively charged bodies.
Despite the fact that it has been positively determined that electron flow is the correct theory, the conventional flow theory still dominates the industry. Either theory can be used as long as the orientations are correct. Conventional flow will be used from this point on in these training modules unless otherwise stated.
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