7th Class Science Electric Current and Its Effects Electric Circuit

         Electric Circuit

We know that when charged particles move, electricity is produced. For continue production of electricity, charge particles required to move continuously. Therefore, a path is prepared through which charge particles (electrons or charged atoms) keep on circulating. Thus electricity is produced continuously.

The path through which charge particles move is called electric circuit.

A simple electric circuit is composed of a battery, wire, and a switch. One end of the wire is connected to the negative terminal of the battery and the other end of the wire is connected to the positive terminal of the battery. Switch is fitted in the wire in such a way that when switch is on, the wires of the circuit are connected and current is passed. When the switch is off, the wires are disconnected and the current cannotpassed through the circuit. Thus the switch gives us the facility of using electrical energy as per our requirement. Different electrical appliances are fitted in the circuit for different purposes.

Switch                      Cell                    Battery

Lamp              Voltmeter             Ammeter

Register             Deregister            Motor  

           Resistance

Resistance is the force that oppose the flow of electrons in a conductor. Resistance of a matter depends on its nature. Generally metals offer lower resistance, whereas non-metals offer higher resistance. Moreover, the resistance of a wire also depends on the thickness and length of the wire.

           Resistance Due to Thickness

If the thickness of the wire is increased, it will offer less resistance and if the thickness of the wire is decreased, it will offer greater resistance.

                 Low resistance

                       High resistance  

            Resistance Due to Length

If the length of the wire is increased, it will offer higher resistance and if the length of the wire is decreased, it will offer less resistance.

            High resistance

                         Low resistance  

              Conductor and Insulator

For the production of electricity a path is needed through which charge particles keep on moving. The substances, which allow the charge particles to move through themselves, are called conductors. In other words, conductors are the substances, which give the way for movement of charge particles through themselves. For example, silver, copper, aluminum, gold etc. are conductors. Insulators are the substances, which do not allow the charge particles to move through themselves .For example, plastic, paper, wood etc..