Question

What is specific resistance?

What do you understand by specific resistance of a solution?

Answer 1

A conductor’s resistance is inversely proportional to its area of cross-section (A) and directly proportional to its length (l).

This means that the resistance (R) varies as the ratio of length to area:

R ∝ l and `R prop 1/A`

Thus, `R prop l/A` or, `R = rho l/A`

where ρ (rho) is the constant of proportionality and is called the specific resistance of the conductor. It may be defined as follows:

If l = 1 cm, A = 1 cm² then we have R = ρ

Hence, specific resistance may be defined as the resistance of the conductor having a length of one centimetre and an area of cross-section equal to one squared centimetre.

Another name for specific resistance is the conductor’s resistivity. Ohm cm or Ω cm are the units of specific resistance.