what is resistivity ? and what is resistance ? differentiate between the two..
Resistance is a measure of the opposition that a circuit (or an electrical element) offers to the flow of electric current. Resistance is dependent on the length and area of cross-section of the conductor. It is measured in Ohms, Ω. Resistance of a conductor changes with temperature.
Resistivity is the measure of a material’s ability to oppose the flow of current. Resistivity of a conductor is a property of the material of the conductor. Unit of resistivity is Ohm meter, Ω m. Resistivity of the material of the conductor changes with temperature.
Example:
We say resistance of the 1 meter long copper wire used in the circuit is 0.5 Ω, total resistance of the circuit is 1000 Ω.
Resistivity of copper is 1.7 × 10-8Ω m at room temperature. There is nothing called resistivity of a circuit.
Following is the equation relating resistivity (ρ) and resistance (R) of a conductor of length (L) and area (A).
Resistance will be numerically equal to resistivity when current flows through a conductor of unit length having diameter equal to 1 m
Differences:
Resistivity | Resistance |
1. It is the measure of a material’s ability to oppose the flow of current. |
1. It is a measure of the opposition that a circuit (or an electrical element) offers to the flow of electric current. |
2. It depends on the property of the material. Its value is constant for a particular range of temperature. | 2. Resistance of a conductor is directly proportional to its length and inversely proportional to its area of cross-section. |
3. Unit of resistivity is Ohm meter, Ω m. |
3. Unit of resistance is Ohm, Ω. |