Charge and Current

An electric current is the flow of electrical charges, typically electrons. When a circuit is complete, charges flow, producing a current. A source of potential difference is also required for current to flow in a circuit. For example, a cell or battery.

The two types of current are:

  • Direct current (d.c.) – Electric current that flows in only one direction
  • Alternating current (a.c.) – Electric current that reverses direction at regular intervals

Charge is the total current that has flowed past a point over a period of time. To calculate the electrical charge flowing through a given point over a period of time, we use the equation:

  • Q = Charge flow in coulombs (C)
  • I = Current in amperes (A)
  • t = Time in seconds (s)

In a series circuit, the current is the same at any point.

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