Solved Problem -2 · Part 3

Conductivity Conductance of a material is the property of a material to aid the flow of charges and hence, the passage of current in it. The conductance of a material is mathematically defined as the reciprocal of its resistance (R). Hence, the conductance ‘ G ’ of a conductor is given by G = ( . ) Its unit is ohm – . It is also represented as ‘mho’. The reciprocal of electrical resistivity of a material is called its electrical conductivity . = ( . ) Its unit is ohm – metre – . It is also represented as mho metre – . The conductivity is a constant for a given material. Electrical conductivity of a conductor is a measure of its ability to pass the current through it. Some materials are good conductors of electric current. Example: copper, aluminium, etc. While some other materials are non- conductors of electric current (insulators). Example: glass, wood, rubber, etc. Conductivity is more for conductors than for insulators. But, the resistivity is less for Electricity conductors than for insulators. The resistivity of some commonly used materials is given in Table . . Table . Resistivity of some materials NATURE OF THE MATERIAL MATERIAL RESISTIVITY (Ω m) Conductor Copper . × – Nickel . × – Chromium . × – Insulator Glass to Rubber to Solved Problem- The resistance of a wire of length m is ohm. If the area of cross section of the wire is × – m , determine its (i) resistivity (ii) conductance and (iii) conductivity Solution: Given: Length, L = m, Resistance, R = ohm and Area, A = × – m Resistivity, =