difference between resistance and resistivity.

Resistance of a conductor is the property of a conductor due to which it opposes the flow of current through it .Resistance of a conductor is numerically equal to the ratio of potential difference across its ends to the current flowing through it.

The resistance of a wire depends on the following factors:

1. Directly proportional to the length (l) of the wire.
2. Inversely proportional to the area of cross-section of the wire.
3. Nature of the material of wire.

combining all we can write that.

.

Here, ρ is the constant of proportionality and is called the electrical resistivity or specific resistance of the material of the wire.

The resistivity will be given as

If l= 1, A = 1, then r = R.

Thus, we define resistivity as the resistance of a wire of that material of unit length and unit area of cross section.