Question

Which among the following is the unit of resistivity?
1. ohm-metre
2. ohm-metre²
3. ohm per metre
4. per ohm per metre

Answer 1

Correct Answer - Option 1 : ohm-metre

The correct answer is option 1) i.e. ohm-metre

CONCEPT:

• Resistance: The hindrance to the flow of current offered by a material is called electrical resistance.
  • The SI unit of electrical resistance is the ohm (Ω).
  • The resistance of a conducting wire is given by the equation:

\(R = ρ\frac{l}{A}\)

Where R is the resistance, l is the length of the wire and A is the cross-sectional area of the material.

EXPLANATION:

Electrical resistivity, \(ρ = R\frac{l}{A}\)

• The SI unit of resistance (R) is Ω, length (l) is m, and that of cross-sectional area (A) is m².

\(\Rightarrow ρ = \Omega (\frac{m}{m^2}) = \Omega m\)

• Thus, the unit of resistivity is ohm-meter.