Question

A wire of length 40 cm and area of cross-section 0.1 mm² has a resistance of 0.8 Ω. Calculate the sp. resistance of the wire.

Answer 1

l = 40 cm; a = 0.1 mm²; R = 0.8 Ω

1 cm² = 100 mm²

\[a = 0.1\ \text{mm}^{2} = \frac{0.1}{100}\ \text{cm}^{2} = 0.001\ \text{cm}^{2}\]

Sp. resistance, \[\rho = \frac{Ra}{l}\]

\[= \frac{0.8 \times 0.001}{40}\]

\[= 0.00002\ \Omega\text{cm}\]