Electric Currents

Current in a circuit is a measure of the flow of charge past a specific point in a circuit.

where DQ is the amount of charge that flows by the point in a time Dt. The unit of current is Amperes or amps (A). One amp is equivalent to one Coulomb per second. Charge is a conserved quantity: it cannot be created or destroyed. Therefore the current that flows into a junction must equal the current that flows out. For instance, if three wires are attached at a point as shown below, the total current flowing into the junction is equal to the total current flowing out:
i1 = i2 + i3


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