Electric Current
The flow of Electric charge particles is called as electric current. In electric circuits the charge is carried by the movement of electrons through a conducting material called as conductor.
The loosely bounded electrons that appear in metals are called as conduction electrons. These conduction electrons move freely throughout the metal and they function as charge carriers. Thus in conductors, the current is due to
negative charge particles. Whereas in semiconductors, the current may due to either positive or negative charge particles. The direction of current is arbitrarily same as the direction of movement of positive charges and it is opposite in the case of negative charge particles i.e. electrons.
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| Electric current shown with flow of electrons |
While solving circuits, the exact direction of current is unknown. So, a reference of direction of currents are chosen arbitrarily. Then after solving, any negative values of currents in the result indicates that the actual direction is opposite to the chosen ones.
Alternating Current-AC and Direct Current-DC:
In DC (Direct current) the charge particles flow in a single direction and it is usually supplied by DC generators, batteries and solar cells. Where as in AC (Alternating Current), the direction of flow of charge particles reverses periodically and it is supplied by alternators.
Units of measurement of Current
The current is conventionally indicated by symbol ‘I’. It is measured by the amount of charge flowing through the circuit over a period of time and is given as:
\[I=\frac{dq}{dt}\]
The SI unit of Current is Ampere indicated with letter 'A'. Ammeter is an instrument used to measure the current.
An ampere is defined as 6.241*1018 electrons (1 Coulomb) per second passing through a point in a circuit.
An ampere is defined as 6.241*1018 electrons (1 Coulomb) per second passing through a point in a circuit.
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