What is Electric current gives its S.I Unit ?||Define current density ? ||State Ohm's law ? Write its Mathematical form ?|| Where " R " is called Resistance|| What is Conductivity ? Give its S.I Unit ?|| Define resistivity (or) specific resistance ? || What are ohmic conductors ?

 

*** What is Electric current gives its S.I Unit ?

Current :-  The  rate of electrical charge through any transaction is called Current.

         

                   i = Q/t

                   i = ne/t

* S.I Unit is " ampere ".

* It is a Scalar.

 

*** Define current density ?

Current density : - Current for unit area is called Current density.

                   J = i/A

* S.I Unit amp/ meter square.

* It is a Vector.

*** State Ohm's law ? Write its Mathematical form ?

Ohm's law :- At Constant temperature the potential difference between the two point of the conductor is directly proportional to current.

*  " V " directly proportional to " i ".

* V= iR

* R = V/i

:: Where " R " is called Resistance.

*** What is Resistance give its unit ?

Resistance :- The Property of the conductor which opposes flow of current is called Resistance.

                            ( OR )

The ratio of electric potential to current passing through the conductor is called Resistance.

                       R = r/i

                      Volt/amp

* S.I Unit " Ohm ".

*** What are ohmic conductors ?

Ans :- The conductors which are obeys ohms law are called ohmic conductors.

Example:- Metals

*** What are Non Ohmic conductors ?

Ans :- The conductors which are doesn't obeys ohms law are called Non Ohmic conductors.

Example :- Insulaters, Semiconductor, thermistor.

*** Define resistivity (or) specific resistance ? 

 Ans :- The resistance of a conductor of unit length and unit cross sectional are is called specific resistance (or) resistivity.

                              ρ = RA/l

* S.I Unit " ohm.m " .

*** What is Conductance ? Give its S.I Unit?

Conductance (G) :- The reciprocal of resistance is Called Conductance.

               G= 1/R

* S.I Unit " Mho " (or) " simen ".

*** What is Conductivity ? Give its S.I Unit ?

Conductivity :- The reciprocal of resistivity is called conductivity.

                σ = 1/ρ

* S.I Unit " Mho/m " (or)  " simen/m ".