Question

Calculate the area of cross-section of a wire of length 2 m. its resistance is 250 ohm and the resistivity is 1.84 x 10 *-6 ohm-m .

Answer 1

Given :

Length of wire, L = 1.0 m

Resistance of wire, R = 23 Ω

Resistivity of wire, ρ = 1.84 × 10⁻⁶ Ω m

To find :

• Area of cross section of wire, A = ?

Formula required :

Relation between Resistance (R), Resistivity (ρ), Length (L) and area of cross section (A)

       R = ρ L / A

[ Where R is in ohms, ρ is in ohm-metres, L in metres and Area in square metres ]

Solution :

Using relation

→ R = ρ L / A

→ 23 = ( 1.84 × 10⁻⁶) ( 1 ) / A

→ 23 = 1.84 × 10⁻⁶ / A

→ A = 1.84 × 10⁻⁶ / 23

→ A = 0.08 × 10⁻⁶  m²

Therefore,

Area of cross section of wire would be 0.08 × 10⁻⁶  m².