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Electricity:- Part 1

1) Charge- It is the force of attraction between the sub atomic particles such as proton, electron and neutron. 

Types of electric charge 
(i) Positive charge- The charge acquired on a glass rod when rubbed with silk cloth is called a positive charge. It is denoted by (+ve) Charge. 

ii) Negative charge- The charge acquired on an ebonite rod when rubbed with woollen cloth is called a negative charge. It is denoted by (-ve) Charge. 

  * Opposite or unlike charge attract each other. 
  * Similar or like charges repel each other. 
  * Benjamin Franklin gave the name of the two types of charge positive and negative. 
  * SI unit of electric charge is Coulomb which is denoted by “C”. 

2) One Coulomb- The quantity of electric charge which exerts a force of 
9 × 109 Newton on an equal charge placed at a distance of 1 metre is called One Coulomb. 
                              ...

Q) Calculate the number of electrons in 1 C of Charge? 
-> As we know that Charge of Electron is 1.6 × 10-19 C. 
So, 
...

 thus, In 1 C of charge, the numbers of electrons are 6.25 × 1018 electrons. 

* Free electrons- The conductors have some electrons which are loosely held by the nuclei of their atoms and these electrons are called free electrons. 

3) Electricity- The physical phenomenon arising from the behaviour of electron and proton that is caused by the attraction of particles with a positive charge and repulsion of particles with the same charge called electricity. 

Electricity are two types:- 
(i) Static electricity- When two bodies are rubbed together, they acquire the property of attracting light objects like small bits of paper, dust particles etc. this property is called static electricity. 

(ii) Current electricity- The rate of flow of charge per unit time is called current electricity or electric current. The direction of current electricity is the direction of flow of positive charge. 

Note:-
* Conductors- Conductors are those materials which allow electricity to pass through themself. 
 E.g. metals like silver, iron, copper etc. 
   -> Earth and moist particles act as a conductor. 

* Insulator- Insulators are those materials which do not allow electricity to pass through themself. 
 E.g. paper, wood, glass etc. 

4) Electric current- The rate of flow of charge per unit time is called an electric current.
  In other words, the quantity of charge flowing per unit time is called an electric current.
              ...
  -> The amount of charge from a current of one ampere flowing for one second is called one coulomb
       Q = It 
* SI unit of electric current is ampere and it is a scalar quantity. 

* One Ampere- The rate of flow of one coulomb of charge flows through any 
cross-section of a conductor in one second is called one ampere. 
                 1 A = 1 C/1 t

* Smaller unit of current is milliampere(mA).
               ...
* The very small unit of current is microampere(μA).
              ...
-> “Ampere” named after the French mathematician Andre Marie Ampere (1775-1836). 

* Electric current is measured by the ammeter. 
   An ammeter is an instrument which measures electric current. It is always connected in series in a circuit. While connecting the ammeter in a circuit, its positive terminal should be connected to the positive terminal of the battery and its negative terminal should be connected to the negative terminal of the battery. 
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Electric circuit
-> Electrons cannot jump freely through the air to the positive terminal of the battery, they need a circuit to move. When a source of energy like a battery is connected to a light bulb, the electrons can move from the battery to the light bulb and vice versa. This arrangement is called an electric circuit. 
  In simple words, we can say that continuous and closed path of an electric current is called an electric circuit. 
               ...

Electric circuits are two types:- 
i> Open circuit- We can stop the current from flowing by attaching a switch into the circuit. Switch act as a conducting link between the battery and the bulb. So when the switch is turned off the current stop flowing and the bulb does not glow. 
  Such a circuit is called an open circuit.

ii> Closed circuit- when current flows through a circuit then that circuit is called a closed circuit.

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Note:- An electrical load is an electrical component or portion of a circuit that consumes (active) electric power. 
  In electric power circuits, examples of loads are appliances and lights. 

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