Define Current

potential difference

The difference in the potentials of two charged bodies is called potential difference.

       Unit of PD is Volt.

Electric Potential

The capacity of a charged body to do work is called electric potential (V).       

Unit is Volt. V=W/Q

Current

The rate of flow of charges is called current.

Current, I  =  Q/ t =  ne / t

Unit of current is Coulomb/second or Ampere.

One Ampere

          One ampere of current is flowing through a wire if at any section one coulomb of charge flows in one second.

Ohm’s Law

       The current flowing through the conductor is directly proportional to the potential difference applied across it.

             I α V

            V/I = Constant, This constant is called resistance (R).

            V = IR

               Ohm’s law defines the relationship between the voltage, current, and resistance in an electric circuit, I=V/R.

The current is directly proportional to the voltage and inversely proportional to the resistance.

laws of resistance

The laws of resistance states that the Resistance “R” offered by a conductor depends upon following factors,

R = ρ L /A,     ρ= resistivity (Specific resistance), L= length of conductor, A= area of conductor

Specific resistance is defined as the resistance offered per unit length and unit cross-sectional area when a known amount of voltage is applied

R=ρ l/A  ,  ρ=specific resistance, l = 1m, a = 1m, then R = ρ