The resistance of 1 m of nichrome wire is 6 Ω. Calculate its resistance if its length is 70 cm.

Given,

1^st case

Length of nichrome wire (l₁) = 1 m = 100 cm

Resistance of nichrome wire (R₁) = 6 Ω

2nd case

l₂ = 70 cm

R₂ =?

By 1^st law of resistance

$\frac{{\mathrm{R}}_1}{{\mathrm{R}}_2}=\frac{{\mathrm{\ell }}_1}{{\mathrm{\ell }}_2}$

$\frac{6\mathrm{\Omega }}{{\mathrm{R}}_2}=\frac{100 \mathrm{cm}}{70 \mathrm{cm}}$

$\therefore {\mathrm{R}}_2=4.2\mathrm{\Omega }$