Physics

ELECTRICITY 

Electricity is the flow of electrical power or charge. It is a secondary energy source which means that we get it from the conversion of other source of energy like coal and natural gas and oil , nuclear power and other natural resources which are called primary sources.

Electrical charges

There are two types of electric charges : Positive and Negative like charges repel each other and unlike charges attract each other

Coulomb's Law

The force between two small charged particles is directly proportional to the product of the charges and inversely proportional to the square of distance between them 

F =q¹q²/r²

F= +{repulsive Force}

F= -Ve{attractive Force}

Classification of materials according to their conductivity

Materials are classified as conductors insulators and semiconductors according to their Electric conductive .

Conductors : 1.Allow charges to flow easily through them 

                      2.can be charged 

Insulators :    1.Do not allow charges to flow through them 

                      2.Cannot be charged

Electric potential it is the work done per unit charge in bringing a charge from infinity to a particular point 

potential difference it is the work done per unit charge in moving a charge from one point to another point 

Flow of charges :Every positive charge moves from a region of higher potential to that of a lower potential whereas a free negative charge moves from lower potential to the region of higher potential  a potential difference is required for the flow of charges.

Direction of conventional current is from positive terminal to the negative terminal direction of electrons is from negative to positive terminal

A cell is a device that maintains a constant potential difference between its terminal for a long time

Electric current :The rate of flow of electric charge is known as electric current 

unit =ampere

1Ampere=1Coulomb/1second

I=Q/t

were I is current measured in amperes 

It is scalar quantity

 Ammeter 

  The meter used for measuring the current is known as a Ammeter.

  The current is the flow of electrons whose unit is ampere. Hence the instrument which measures the flow    of current in amperes is known as  ampere meter or Ammeter

 Symbolic representation of a metre

 CONNECTION OF AMMETER IN THE CIRCUIT

 The ammeter is connected in series in the circuit always

VOLTMETER 

 Voltmeter is a voltage meter which measures the voltage between two nodes  that  is it is a device used to   measure potential difference it is always connected in parallel in the circuit.

Symbolic representation of a voltmetre

CONNECTION OF VOLTMETER IN THE CIRCUIT