The specific resistance of a conductor increases with

Answer

4R from O

Explanation

`y_(cm) = ({rho(pi(2R)^(2))/(3) xx 4R} xx R + {12rho xx (4)/(3)piR^(3)} xx 5R)/({rho(pi(2R)^(2))/(3) xx 4R} + {12rho xx (4)/(3)pi4R^(3)}) = 4R`