# A material ‘B’ has twice the specific resistance of ‘A’. A circular wire made of ‘B’ has twice the diameter of a wire made of ‘A’. Then for the two wires to have the same resistance, the ratio AA /AB of their respective lengths must be ?

SHAIK AASIF AHAMED
8 years ago
Hello student,
$\dpi{80} R1=\frac{\rho _{a}l_{a}}{\pi R_{a}^{2}}$
$\dpi{80} R2=\frac{\rho _{b}l_{b}}{\pi R_{b}^{2}}$
so we get$\dpi{80} \frac{l_{b}}{l_{a}}=2$
Thanks and Regards
Shaik Aasif