Page 122 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

13 Electric Current & Its Effects
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Chapter in a Nutshell

v Electric current or electricity is the flow of electric charge.
v The materials which allow electric current to pass through them are called electric
conductors. For example, copper, aluminium, etc.

v The materials that do not allow electric current to pass through them are called insulators.
For example, rubber & plastic.
v A continous conducting path between the two terminals of a cell or battery along which

electric current flows, is known as an electric circuit.
v Two types of electric circuits are–open circuit & closed circuit.
v When there is a break in the continous path of electric current, the circuit is said to be open.

No electric current flows in an open circuit.
v When there is no break in the continuous path of current, the circuit is said to be closed.

Electric current continuously flows in a closed circuit.
v In an electric circuit, a switch is used to control the flow of electric current.
v When the switch is in the ON position, the circuit is closed & when the switch is in the OFF

position, the circuit is open.
v An electric circuit can be drawn with the help of symbols that represent the electronic

components. Such a representation of an electric circuit is called an electric circuit diagram.
v Circuit diagrams help us to easily represent the complex circuits.
v An electric cell produces electric current with the help of the chemicals stored in it.

v A battery is a combination of two or more cells.
v One end of a cell or a battery is positive (+) & the other end is negative (-)
v To obtain a battery, the cells need to be placed one after the other so that the positive

terminal of one cell is connected to the negative terminal of the following cell.
v If we join two positive terminals or two negative terminals, the battery obtained will not
work.

v An electric bulb ia a device which produces light when electricity is passed through its
terminals.

v The filament of a bulb is made of tungsten, that has a very high melting point.
v A bulb is said to be fused if the filament is broken.
v Short circuit is a problem in an electrical circuit when two or more wires, touch each other.

v An electric current can produce three effects – heating effect, magnetic effect and chemical
effect.

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