Electric Current

Electric Current

INTRODUCTION
*Electricity travels along a path.
*The whole path along which electricity travels is known as a circuit.
*The flow of current from +ve terminal to -ve terminal is along the circuit.
*The flow of current from -ve terminal to +ve terminal is with in the cell.
*An unbroken path flow two terminals of an electric cell is known as a closed circuit.
*Electricity will flow in a closed circuit.
*A broken path is known as an open circuit  in b/w the two terminals of an electric cell.
*Electricity will not flow in an open circuit.
*Electric current has electrical energy which comes from electric cells.
*Electric current from cells flows in one direction only.
*A switch is a device to ‘close’ or ‘open’ a circuit.

The Dry cell:  A Dry cell is a type of electricity-producing chemical cell,commonly used today for many home and portable devices, often in the form of batteries.
    
*It was developed in 1886 by the German scientist Carl Gassner. 
*Also Electric cell being used in torches, transistors, toys, watches, clocks, calculators and other electrical appliances.
    +ve terminal  =Carbon rod             
    -ve terminal     =zinc rod         
    electrolyte= Ammoniumchloride paste(NH₄Cl).


Battery :
*A combination of two (or) more cells is called a battery.
*A battery of cells is represented by the symbol         
*A electric cells may be dry cells, button cells, batteries, accumulators (or) solarcells.


Button cells:
Buttoncells are small like a button. They are used in wrist watches, calculators, mini-microphones and the ear devices.                     
*These cells are made from nickel (Ni) and cadmium.
*They will give more electrical energy than large sized cells. 
*They have longer life and occupy less space


Car battery and a mobile phone battery:
A car battery (or) the batteries being used in buses and trucks are a combination of one more cells inside. 
*They can supply more current than a dry cell.                  
*They can be recharged with the help of an electric charger and used up again and again.        
* For this property, these batteries are also called accumulators


Solar cells:Solar cell converts solar energy  into electrical energy. This energy is used either directly (or) is stored in an accumulator.