# What is resistance and resitivity?

Dear Student,

**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.

Following is the equation relating resistivity (ρ) and resistance (R) of a conductor of length (L) and area (A).

$R=\rho \frac{L}{A}$

**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. |

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