Question

The resistivity of nichrome is 10^-6 Ωm. What length of a uniform wire of this material and of 0.2 mm diameter will have a resistance of 200 ohm?

Answer 1

Given: ρ = 10^-6 Ω m, d = 0.2 mm,

∴ r = 0.1 mm = 0.1 × 10^-3 m, R = 200 Ω

To find: Length (l)

Formula: R = \(\frac{ρl}{A}=\frac{ρl}{\pi r^2}\)

Calculation: From formula,

l = \(\frac{\pi r^2}{\rho}\)