Question

A wire has linear resistance $\rho$ (in ohm/m). Find the resistance R between points A and B if the side of the ‘‘big’’ square is d :

• A. $\frac{\rho d}{\sqrt{2}}$
• B. $\sqrt{2}\rho d$
• C. $2\rho d$
• D. None of these

Answer 1

The correct option is A

$\frac{\rho d}{\sqrt{2}}$

$r=\frac{\rho d}{2}$

$R=\frac{1}{2}[2r+\frac{2r\left(r\sqrt{2}\right)}{(2+\sqrt{2})r}]$

$=r\sqrt{2}$

$R=\frac{\rho d}{\sqrt{2}}$