Question

The length and area of cross-section of a conductor are doubled, its resistance is

• A. unchanged
• B. halved
• C. doubled
• D. quadrupled

Answer 1

The correct option is A unchanged

Resistance $R=\rho \frac{L}{A}$

Given : $L^{\prime }=2L$ $A^{\prime }=2A$

$\therefore$ New resistance $R^{\prime }=\rho \frac{L^{\prime }}{A^{\prime }}=\rho \frac{2L}{2A}=R$

$⟹$ Resistance remains the same.