Physics 2014 JAMB Past Questions - Question 37: If a metal wire 4m long and cross sectional area 0.8mm² has a resistance of 60.find the resistivity of the wire .

Correct Answer

B

Explanation

Resistivity, p = RA/t=6x0.8x10-6 = 1.2x10-6 Ω To find the resistivity of the wire, we can use the formula:

Resistance (R) = (Resistivity (ρ) * Length (L)) / Cross-sectional Area (A)

Given:
Resistance (R) = 6 Ω
Length (L) = 4 m
Cross-sectional Area (A) = 0.8 mm² = 0.8 × 10^(-6) m²

Substituting these values into the formula, we can solve for the resistivity (ρ):

6 Ω = (ρ * 4 m) / (0.8 × 10^(-6) m²)

Rearranging the equation, we get:

ρ = (6 Ω * 0.8 × 10^(-6) m²) / 4 m

Simplifying the expression, we find:

ρ = 1.2 × 10^(-6) Ω·m²

Therefore, the resistivity of the wire is 1.2 × 10^(-6) Ω·m².