Wednesday, 15 January 2014

Physics Made Simple : Electric Current

Electric Current

When electric charges are moving across any surface,we say electric current is flowing through that surface.

The rate of flow of electric charge through any cross sectional area is called Electric Current.

If Charge Q is passing through an Area A in time “t” second,then the electric current flowing through it would be I

I = Q/t


In SI (System International), the init of current is known as Ampere.

Electric charges are of two kinds : positive and Negative.

Electric current is produced due to flow of both positive and negative charges.


Conventional Current

Consider there is a metal cup.

A stream of positive charges is being injected into a metal cup.As there is a movement of electric charges taking place,we will say an electric current is flowing through upper cross sectional area of this cup.

The result of this movement is the amount of positive charge increases in he cup.

If we stop the injection of positive charges now and instead start to inject negative charges,the positive charges stored in electric cup would start getting neutralized.

In other words, the effect of flow of negative charges is the same as effect produced by flow of positive charges in opposite direction to flow of negative charges.

We can safely say that the current produced by the flow of negative charges is equivalent to a flow of current of an equal amount of positive charges in the opposite direction


This equivalent current of positive charges is known as conventional current.



   

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