Electric current and circuit:What is electric current?Let us know about that. We are very much familiar with water current and air current.The flow of water constitutes water current in rivers or canals.The flow of air constitutes air current.Similarly the flow of electric charge in a conductor is called electric current.For example: Let us consider working of a torch light.Torch light contains cell or battery, bulb and switch.When switch is on the cell or battery provides flow of charges or an electric current through the torch bulb to glow.If the switch is off current does not flow and bulb does not glow.Actually a switch makes a conducting link between cell and the bulb. A continuous and closed path of an electric current is called an electric circuit.Parts of electric circuit are called electrical components. They are, Bulb, battery, switch and connecting wires.How the electric current is expressed?.Electric current is expressed by the amount of charge flowing through a conductor in limit time.OrWe can say that the rate of flow of electric charges.What is the direction of the electric current?Actually in circuits electrons constitute the flow of charges. But conventionally in an electric circuit the direction is taken as from positive to negative.If a net charge "q" flows through conductor in time "t" then the current I is q by t.The SI unit of electric charge is column.This is nearly equal to charge of 6 x 1018 electrons.We know that charge of an electron is negative charge of 1.6 x 10-19 Coulombs.Measuring of an electric current:The electric current is expressed in ampere, named after the Andre-Marie Ampere.One ampere is constituted by the flow of one column of charge per second. i.e., small quantities of current are expressed in milli amperes and micro amperes.Ammeter is a device which is used to measure the current in a circuit connects in series.

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