cbse notes for class 10th science || Science notes class-10th Chapter-12 Electricity ||Science notes class-10th

Cbse Science notes class-10th

Chapter-12 Electricity 

•Charge is a fundamental particle in an atom it may be positive or negative.

•like charges repel each other.

•Unlike charges attract each other .

Coulomb(C):S.I unit of charge

1 Coulomb charge=charge present on approx 1.6×10¹8 electrons

•Charge on 1 electron =Negative charge of 1.6×10¹9C

              Q=ne

Where     Q=charge (total)

                 N=No.of electrons

                 E=charge on 1 electron

Current(I):The rate of flow of charge is called current.

         Current=Charge

                        –––––––

                          Time

         I =Q

             —

              T

    S.I unit of current =Ampere(A)

               1A=1C s¹

               1mA=10³ A

               1uA =10 6 A 

 Current is measured by Ammeter its symbols is  

Ammeter has low resistance and always connected in series.

Direction of current is taken opposite to flow of electrons as electrons were not known at the time when the phenomenon of electricity was discovered first and current was considered to be flow of positive charge.

Potential Difference(V):work done to move a unit charge from one point to another.

V=W         

     —

     Q

            

1 volt:when 1 joule work is done in carrying one coulomb charge then potential difference is called 1 volt.

 S.I unit of potential difference=volt(v)

                                                     1V=1JC¹

1 Volt :when 1 joule work is done in  carrying one coulomb charge then potential difference is called 1 volt.

Voltmeter:Instrument to measure potential difference.

•It has high resistance and always connect in parallel symbol is 

•Cell is the simplest device to maintain potential difference.

•Current always Flow from higher potential to lower potential.

Ohm's law:Potential difference across the two points of a metallic conductor is directly proportional to current passing through the circuit provided that temperature remains constant.

•Mathematical expression for Ohm's law:                                                        

V Proportional I

V=IR

R is a constant called resistance for a given metal.                                             

•V-1 graph for ohm's law:                     

Resistance(R):It is the property of a conductor to resist the flow of charges through it.

•Ohm

: S.I unit of resistance.

•1 Ohm=1volt/1ampere

 

Where potential difference is 1 V and current through the circuit is 1A  , then resistance is 1Ohm.

Rheostat:Variable resistance is a component used to regulate current without changing the source of voltage.

Factors on which the Resistance of a conductor depends: