Question

Aluminium wire has radius 0.25 mm and length 75 m.R=10 ohm. Calculae the resistivity

Answer 1

$\underline\bold{\huge{Answer !!}}$

Radius = 0.25 mm
Length = 75 m
Resistance = 10 ohm


Area of cross-section

$= > \pi {r}^{2} \\ \\ = > \frac{22}{7} \times ({0.25})^{2} \\ \\ = > \frac{22}{7} \times0.625 {mm}^{2} \\ \\ = > \frac{22}{7} \times 0.625 \times {10}^{ - 6} {m}^{2}$
Resistivity

$= \frac{resistence \times area \: of \: cross \: section}{length} \\ \\ = > \frac{10 \times \frac{22}{7 } \times 0.625 \times {10}^{ - 6} }{75} \\ \\ = > \frac{ \frac{22}{7} \times 0.25 \times {10}^{ - 6} }{3} \\ \\ = > \frac{3.14 \times 0.25 \times {10}^{ - 6} }{3} \\ \\ = > 1.04 \times 0.25 \times {10}^{ - 6} \\ \\ = > 0.26 \times {10}^{ - 6} ohm \: m$