Question

1. State the relationship between the resistance R of a wire to its length l and cross-sectional area A. Use the mathematical symbols to arrive at the final formula.
2. Using the formula, define the resistivity of a material.

Answer 1

A. `R ∝ l`

`R ∝ l/A`

R = `ρ l/A`

B. R = `ρ l/A`

𝜌 = `RA/l` for A = 1 m² and l = 1 m, we have

𝜌 = R

Hence, resistivity is the resistance offered by a wire of length 1 m having a cross-sectional area of 1 m².