Electric Current

•    Electric current is defined as the rate of flow of electric charge. Its SI unit is ampere (A). When one coulomb of charge flows through an electric circuit in one second then the current flowing through the circuit is said to be one ampere.
•    Electric cells are the sources of direct current. Direct current has constant magnitude that flows in one particular direction. In electric cells chemical energy gets converted into electrical energy.
•    Electric Cells are of two types – primary cells and secondary cells.
Primary cells are the cells in which the chemical energy gets converted into electrical energy through an irreversible chemical reaction and hence, these are not rechargeable.
Secondary cells are those cells in which chemical energy gets converted into electrical energy through reversible chemical reaction and hence, these cells are rechargeable.
•    Electric cells are important electric components. Electric components are the devices that are used in an electric circuit. Electric bulb, electric cell, key, ammeter, voltmeter, galvanometer, etc. are some examples of electric components.
•    An electric circuit is defined as a closed path through which an electric current can flow.  Electric circuit is either closed or open.
Closed circuit is the one which is complete and current can flow through it.
Open circuit is the one which is incomplete or broken and current cannot flow through it.

                                                 

•    On the basis of permissibility of current flow through different materials, materials are classified as conductors and insulators.
Conductors are the materials which allow the flow of electric current through it. All metals are good conductors.
Insulators are the materials which do not allow the flow of electric current through it. Wood, plastic, etc. are some examples of insulators.

 

 

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  • Q1

    What is the function of rheostat in an electrical circuit?

    Marks:2
    Answer:

    Rheostat is a device, used to control the amount of current flowing in the circuit.

    The current is controlled by varying the value of resistance with the help of jockey connected to it.

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  • Q2

    What is the role of resistance in electric circuit? How the resistance is related to current flow in the circuit?

    Marks:2
    Answer:

    The main function of resistors in a circuit is to control the flow of current to other components.

    If the value of resistance increases then, amount of current flow will decrease and vice-versa.

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  • Q3

    What is the role of electric switch in an electric circuit?

    Marks:1
    Answer:

    Electric switch is a device which completes or breaks the circuit.

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  • Q4

    Define electric current and give its SI unit.

    Marks:1
    Answer:

    Electric current is defined as rate of flow of electric charge. The SI unit of electric current is ampere (coulomb/second).

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  • Q5

    What type of energy transformation takes place when current is drawn from the electric cell?

    Marks:1
    Answer:

    During the current drawn from the cell, the chemical energy gets converted into electrical energy.

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