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# Electrical Resistivity Electrical Conductivity

Electrical resistivity of a conductor is a measure of the resisting power of a specified material to the passage of an electric current. It is a constant for a given material.

ELECTRICAL RESISTIVITY ELECTRICAL CONDUCTIVITY

## 1. Electrical Resistivity

You can verify by doing an experiment that the resistance of any conductor ŌĆśRŌĆÖ is directly proportional to the length of the conductor ŌĆśLŌĆÖ and is inversely proportional to its area of cross section ŌĆśAŌĆÖ. Where, Žü (rho) is a constant, called as electrical resistivity or specific resistance of the material of the conductor.

From equation (4.4), Žü = RA/L If L = 1 m, A = 1 m2 then, from the above equation Žü = R

Hence, the electrical resistivity of a material is defined as the resistance of a conductor of unit length and unit area of cross section. Its unit is ohm metre.

Electrical resistivity of a conductor is a measure of the resisting power of a specified material to the passage of an electric current. It is a constant for a given material.

## 2. Conductance andConductivity

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 ŌĆśGŌĆÖ of a conductor is given by

G = 1/R   (4.5) Its unit is ohmŌĆō1. It is also represented as ŌĆśmhoŌĆÖ.

The reciprocal of electrical resistivity of a material is called its electrical conductivity. Its unit is ohmŌĆō1 metreŌĆō1 . It is also represented as mho metreŌĆō1. 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 conductors than for insulators. The resistivity of some commonly used materials is given in Table 4.2. ### Solved Problem

The resistance of a wire of length 10 m is 2 ohm. If the area of cross section of the wire is 2 ├Ś 10ŌĆō7 m2, determine its (i) resistivity conductance and (iii) conductivity

### Solution:

Given: Length, L = 10 m, Resistance, R = 2 ohm and Area, A = 2 ├Ś 10ŌĆō7 m2 Tags : Definition, Formula, Solved Example Problems , 10th Science : Chapter 4 : Electricity
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10th Science : Chapter 4 : Electricity : Electrical Resistivity Electrical Conductivity | Definition, Formula, Solved Example Problems