Textbook Example 16.3

An aluminium wire is 15 m long, has cross-sectional area 3 × 10⁻⁶ m² and resistivity 2.82 × 10⁻⁸ Ω m. Find resistance.

ایلومینیم تار کی لمبائی15 m، مقطع3 × 10⁻⁶ m² اور مخصوص مزاحمت2.82 × 10⁻⁸ Ω m ہے۔ مزاحمت معلوم کریں۔

Solution & explanation

All given quantities are already in SI units.
Use resistance of a uniform wire.
$R = \frac{L \times ρ}{A}$
Substitute.
$R = \frac{42.3}{300}$
Divide length by area.
$\frac{L}{A} = \frac{15}{\frac{3}{1000000}} = 5 \times 10^{6}$
Multiply coefficients and add powers of ten.
$R = \frac{14.1}{100} = 14.1 \times 0.01$
State resistance in ohms.
$R = 0.141$

R = 0.141 Ω

Independent study material · English-medium textbook p. 116 · Original book ↗